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
you are what we in the industry like to call a "lost cause," champ
At some point its been patched so you can reach the end with a ton of money left over and only do one or two things I would rather not. Oh and one I would never but that's not about spending money. That's when the in laws break in. There is no good option.