What is the point of being a “high net worth” person — of being seriously rich? As wealth increases, its benefits seem to diminish, or at times, lead to major problems.

It is easy to see the benefits of having enough money to afford a nice house or two, private education and healthcare, the best food, expensive cars; not having to worry about what you spend. But you do not need dozens or hundreds of millions for these. Let us say ￡20m in capital and property combined, and an income of about half a million, should do the trick.

A simple game illustrates why it is pointless to want more than that, unless you have an unusual reason to do so (like a passion for a particular benevolent cause or a burning desire to fly to the moon).

Suppose you have the UK’s national average wage, nearly ￡28,000. Now I am going to double that, for no additional work hours or change in role. For a short time you feel good, sure. But only six months later, you are already moving the goalposts, spending more and expanding your consumption horizons to fit ￡56,000.

Six months later we repeat the exercise — double the money again. With ￡112,000 to play with, you feel a rush of excitement. But again, how long before that wears off and the newly moved goalposts of aspiration eat it up?

Six months later we double it again, and so on. At what point does the doubling begin to become meaningless; ￡57,344,000, ￡114,688,000, ￡229,376,000, or more than that? There are only so many boats, planes or houses one can buy.

All sorts of new problems will have arisen as you accelerate up through the millions.

I have seen my rich friends fuss at expensive restaurants if the cutlery is not spotless, the ￡500 bottle of wine not quite right. I have looked on as they waited years for their dream houses to be completed. But worst of all, I have seen the effects of inherited wealth.

The impact on offspring is usually dire. I have known well about 50 people who inherited enough money never to need to work. I can think of only one — incidentally, a therapist — who was not severely handicapped by their wealth.

Most of the rest never achieved anything in their careers, insofar as they attempted one. A few became ferocious workaholics, seeking to outdo their forebears, living miserable and frenzied lives. Worst of all, nearly all of them suffered a variety of depression, anxiety and substance abuse, living sad and emotionally unhealthy lives.

I am not remotely suggesting that absolute poverty is the route to wisdom and emotional health, although it is true that many poor countries have far lower prevalence of mental illness than rich ones.

For example, only 4 per cent of Nigerians have suffered a mental illness in the past 12 months, compared with 26 per cent of Americans — invariably the most mentally ill country in all surveys, despite being one of the richest.

The problem is relative, not absolute, deprivation: the more we have, the greater our tendency to keep up with the Joneses; to engage in malignant social comparisons and conspicuous consumption.

Huge wealth seems to drain life of meaning for its owners and their offspring. That this capital could be serving the wider community is a secondary, political issue. My point is, high net worth seems to produce low net self-worth and greater vulnerability to mental illness.