Its a great game you're literally just missing all the sarcasm and humour of the game dude, the aim isnt to just spend his money its to spend his money your way and get the different endings.
I think your missing that spending that amount if money "my way" isnt possible in the game.
I played it all the way to the end.
It isnt physically possible to reach the end without spending money on things I would NEVER spend money on. Even if I had unlimited money.
I think you're also missing the point that he doesnt have that money. You aren't spending his money your way because he doesnt have that to spend. He'd have to liquidate every asset he controls to have most of that and he'd lose about 30-40% to various taxes in the process