This is another in the many ways dubs are fed b.s. they take a cliche - rich people are miserable - and apply it as balm to those who have little or nothing. The implied message is, "but YOU have The Truth and that's more valuable than money!"
I know many wealthy people, a handful of them quite well. They do not appear to be unhappy to me. Do they have the same problems the rest of us do? Sure. Are their lives tragedy-free? No. But, from what I've seen, having money makes life's problems much easier to cope with. The dubs ignore the bible principle: Money is a protection.