People need to realise certain things, firstly billions in the bank owned by several key people leaves a lot of money banks can "play with" and loan out to business's because the chances of a guy with 30billion taking out more than 50million are slim to none, I mean the best/biggest house in the world might be bought, and only cost a couple hundred mil.
Banks need a stable money source, a billion people with £1000 each in the bank gives them very little leeway for lending money because, well any single person could easily take out 1k at a time.
Likewise, often purchases of things like the top end Ferrari's, or other "extravegant" purchases do MASSIVE things for everyone and the economy.
Firstly there are jobs created when someone builds a 100million house, and lots of people make money, and those people pay lots of tax. A billionaire that spends 500million a year buying cars, holidays, houses, boats, generates a lot of tax income. A lot of innovations, increased efficiency engines start off in the most expensive cars, people pay off the research done to make the best cars in the world by buying them, paying the people working to build them, paying a massive tax bill when buying the car in this example, and the technology trickles down to low end cars that end up more efficient and cheaper to run in the future.
But technologies that would be too expensive to research and test in the top end cars if no one bought them.
Frivolous and extravagent spending, just puts money into the economy, people pay to eat in better restaurants, more jobs are needed, more tax is paid on higher quality food, which is sourced from higher quality organic farmers etc, etc.
Rich people pay FAR more tax on their earnings and pay far more tax a year as they spend massive amounts of money.
Giving it away, certainly isn't terrible, and most people who have over 100million in the bank wouldn't notice if they gave away half their wealth, or a lot more. But if every billionaire evened out the wealth of the planet by giving their money away, millions of jobs would be lost, and trillions in tax lost also.
This is all ignoring the massive scam that so many charities are, that waste the money, or hire lots of CEO's, board members and pay celebrities to be involved and lots of the charity donations are lost in the mix. The london Marathon being a good example, the % of cash generated that ends up in charities hands is embarassingly low. IE it should be 99%, and its no where close, generates a HUGE profit for the people that run it, and many many charities are the same.