Don't assume! THINK!
In contemporary profit-driven, capitalistic and wealth-worshipping Western societies people tend to lose perspective and fail to realise that the value of wealth/money is totally subjective.
That's about four sweeping assumptions in one sentence, which must be getting close to a world record (even for this place).
Claiming that the inhabitants of "Western Society" are somehow more materialistic is something of a cliche, but I have yet to see anybody produce any actual evidence to support this assertion. Oddly enough, the response of the rest of the world to, for example, the obvious affluence of modern American society is not to laugh at the USA's fixation with material wealth and but to complain that they are not getting their share, and by the way can you spare a few billion?
Just because 21st century America is actually better than 18th Century America (or 21st Century Peru, Kenya or wherever, at producing material goods is no reason to suppose that the people concerned are any more or less materialistic and profit driven than either their predecessors or any one else in the world. They're simply better skilled with better technology and operating in a socio-economic enviroment that allows them to apply those skills and technology in a productive manner.
The fundamental problem of utilitarianism is that whereas it might seem obvious to you that an extra dollar will bring more pleasure to a poor man than a rich one, it's just an assumption. For all you know Bill Gates may chortle with glee every time a copy of Windows XP is sold whilst the vagrant on the street may spit in your eye when you offer him a ten dollar bill. Value and wealth, as you have said, is entirely subjective, so how can you make objective assessments about either of them?
Attempts at achieving wealth redistribution in order to improve the sum total of human happiness as suggwsted always fall over due to two fundamental flaws -
One - Consider this, suppose you took away every cent of dear William's $50 billion and shared it out amongst the rest of his fellow Americans; they'd all get around $170 dollars apiece. That's not exactly going to make a lot of difference is it?
See there simply aren't enough extremely rich bastards to go round. Which is where this sort of argument always falls down. The idea of "tax the rich!" always ends up with the reality of "tax the moderately well off!" It's never the Williams' of this world that lose out. (In any case the super-rich can afford better lawyers and accountants than the government to pick their way through the tax laws and can always piss off to a jurisdiction more amenable to their requirements if that doesn't satisfy.) It's the guy in the next street who put the effort and graft into building up his own business that gets hit, the woman whose parents scraped and sacrificed to get her through medical college that loses out in favour of the people who simply couldn't be bothered.
Wealth redistribution simply ends up penalising the successful and rewarding those who just want to lie bank and have another beer and that is no way to run a society.
Please note; none of this detracts from the fundamental moral requirement for a society to provide for the destitute and the needy. We are not talking here of preventing death and starvation, we are talking money from person A and giving it to person B just to make person B happier.
Two - Whereas you might think that sacrificying a little economic efficiency to achieve some more social equity is a morally valid trade off, your competitors in the world economy ain't necessarily going to think the same way.
Wake up and smell the coffee, ever heard of the global economy? Today's minor economic efficiency is tomorrow's economic slump when you find the Japanese have stolen all you market share.
To actually address the subject;
There is no correlation between material wealth and happiness
Happiness is a state of mind and it's all down to you. It is not the business of government or society or any institution to cater for any individual's happiness. You happiness is your business to pursue in whatever you wish as is your right.