Of course it is! The market doesn't have 20B$ worth of contractors to build homes so just by injecting that much money your house prices will increase, making i

Of course it is! The market doesn't have 20B$ worth of contractors to build homes so just by injecting that much money your house prices will increase, making it hard for everyone else to build their own home. To get 20B$ in actual money to pay the above-mentioned contractors, you need to sell an additional 7.4B$ in shares (to pay the taxes). Selling 27B$ of your portfolio would inevitably mess with Amazon's stock price, the value of the company would tank and now your 20B$ endeavour effectively cost you 40B$ (remember he doesn't have 136B$ in currency in a vault). Those homes that you are building needs to have clean water and will consume electricity, this is a maintenance cost that homeless people might not be able to afford so there is a yearly price to this endeavour unless you want to go back to square one. On top of that, the grid can't handle the surge that all these new homes require, you need to scale the producing capacity. This puts an additional strain on the global supply chain, again raising your prices. Of course the above is just one big conjecture, but the point I am trying to get across is that it is never simple when these amounts of money are involved because other constraints will emerge that will limit what you can do with your seemingly unlimited amount of money.