Nothing about this couple suggests affluence. His arms are covered with tattoos. They both appear shabbily dressed. Their speech doesn’t suggest much education. The car in which they arrived isn’t very new or impressive.

But as I watch them interact with each other and their son — who’s about 2 years old — I’m struck by how happy they seem to be as they eat together in this restaurant.

They both interact tenderly and lovingly with their son. When the man gets up to get a drink refill, he pauses to kiss the woman on the forehead — and she smiles in love.

I can’t know how much money they make, of course, but everything in my experience with such people suggests it wouldn’t be much. I’d be surprised if they made more than $40,000 combined. Maybe $50,000. I’m just guessing, of course.

But I’m thinking about this because of an article that NPR published today lamenting how difficult it can be to have enough money if you make $100,000 or more a year. It details the horrors of four individuals or families struggling with incomes of $100,000 or more.

The underlying assumption that most people have about money is wrong. They believe they will be happy if just can just get “enough” — but people who believe that seem to find they never have enough. Why?

In 2010, a study by Princeton University researchers found there’s an optimum level of income for happiness. They discovered that as people made more money, their happiness with life increased — up until they hit $75,000. At that point, people didn’t get any happier as their incomes climbed.

There are several lessons here and the NPR story makes me suspect most people still don’t understand those lessons.

If you have a decent income — let’s call it $85,000 to adjust for inflation over the last seven years — you will have a stable financial life if your expectations match your income. If you make $100,000 and you spend every penny of it, you’re going to be in trouble when the inevitable crisis hits. (The brain-dead NPR story doesn’t seem to consider that point.)

If you make $100,000 a year and spend all of it, you’re going to be in trouble when a crisis hits. If you make $500,000 a year and spend all of it, you’re also going to be in trouble when a crisis hits. After you have enough money to live a decent middle class life — not a life of luxury, but one of modest comfort — there’s no reason to keep increasing your spending just because you make more money. This is why you have no money when a financial crisis hits you.

If you are unhappy with your life, you inevitably turn to spending money to increase happiness if you can, but it doesn’t work. If you’re unhappy because you don’t have love or satisfaction or understanding or whatever your basic needs are, having more cars or boats or vacations or a bigger house aren’t going to change that.

I have a friend who owned a beautiful lake home where he and his wife lived. They had no debt. He had a six-figure income and was very comfortable. He and his wife have no children, but she decided she wanted a bigger house. So she talked him into selling their home and buying a much bigger house on the same lake. They don’t use much space in the 4,000-square-foot house they bought. Their expenses are vastly higher now. There’s more to go wrong in this huge house. They have a massive mortgage payment.

The bigger house initially seemed great, but after a few months, they were no happier — and now they’re struggling in spite of his sizable income.

I know what it’s like to squander a large income, because I used to make plenty of money in the best days of my political consulting life. What exactly did I spend that money on? I’m not sure now. I just know I have nothing to show for it.

Over most of the last 10 years, I’ve dealt with a shrinking income and the humiliation of having to change everything about my lifestyle. I lost the place I was living in a nice neighborhood. I had to learn to live on far less than I once made. But it’s forced me to realize that the things I used to spend money on didn’t make me any happier than I am today.

That’s not to say I don’t need more income. That’s why I recently started selling real estate. (I’ve talked about this a couple of times recently already.) I expect to be back above the $85,000 income mark next year for the first time in quite awhile. I see no reason I won’t hit $200,000 a year (and probably much more) in the years after that.

But you know what’s going to be different this time? When I can make $200,000 (or whatever), I’m going to keep living a lifestyle that’s more like that of someone who makes $50,000 or $75,000. (The theft we call taxes skews how to really compare those in real terms, because the levels of theft get higher as you make more money. That’s a different issue, though.)

It’s not that I don’t like the things money can buy. I have a list of things I want to buy as I can afford them. Some cost hundreds of dollars. Others cost many tens of thousands of dollars. But as I acquire the things on my list, I don’t intend to keep expanding my expectations.

I don’t expect to spend hundreds of dollars every month for cable television service. (I know many people who do this and it appalls me.) I don’t expect to buy every new toy and gadget that’s marketed toward people with money. I don’t intend to replace my car all the time — just because I can.

I don’t intend to make the mistakes that are typically made by people who can make $100,000 or more every year and still find reasons to complain they don’t have enough.

So here’s the bottom line.

Lack of money can make you miserable. It can create stress in marriages as people feel under pressure to make more and buy more things. It can drive couples apart when they have different expectations — and when one or both of them try to get their satisfaction in life from acquiring things. If you have trouble paying bills — even at a basic level — it can create fear and shame, destroying relationships.

If you have enough money to live comfortably, you can be just as happy as money can make you at somewhere around $85,000 a year. (Your specific minimum might vary a bit, but it won’t be much more than that.) If you live reasonably — and spend less than you bring home — you can be happy in all the ways that money will ever make you happy.

But if you make larger incomes — even if it’s millions of dollars a year — you will never escape financial pressure and unhappiness if you keep spending money like a drunken sailor. If you don’t have a plan and if you don’t have the maturity to understand that money in itself won’t fix your other problems, it won’t matter how much money you ever bring in. It will never be enough.

The NPR article today appalled me, but it’s not because I don’t have empathy for those people who are struggling. It’s simply that I think they — and most people in the mainstream today — have bought into false ideas about what’s necessary to live a happy and successful life.

I want more money. I need more money. I’m starting to make more money. But I don’t expect the increased income to bring me happiness. I’m not going to buy things in a mad rush to keep up with others or to somehow make myself happy with “stuff.”

There are many reasons that this country is in trouble right now. We have political, economic and cultural issues. But one of the largest is that very few people know how to manage their expectations and live like responsible adults.

For most families — especially those with good incomes — the problem isn’t lack of money. It’s lack of a shared vision between husband and wife for what family and home life ought to be.

If you have a life that is emotionally and psychologically empty, you’re going to try to fill the void with material things. It will never work — no matter how hard you keep running on that eternal hamster wheel.

Find your happiness in genuine mutual love. You will never find you happiness in more money or material things.