Depending on where you live, wouldn't $5M be about enough?
Depending on where you live a house could easily cost above $5M.
Could you be happy (for example) in a comfortable middle-class life?
Yes.
Seriously, why would anyone want $20 Billion Dollars?
Then they can do things like this :
https://bitcointalk.org/index.php?topic=2418909.0 .
Once your basic needs are met, extra money won't do much for you.
That sounds like an extremely cyncical view of life. There is more to life than meeting your basic needs.
$5 million doesn't go as far as you think.
There are paintings that cost hundreds of millions of dollars.
$5M will disappear if all you're trying to do is live comfortably in an expensive American city within a few years.