Starting a business self-selects for people that desire money (over other benefits).

The purpose of a business is money (otherwise you start a hobby or charity or something non-businessey).

Being very successful at business is a selection bias for people that are highly competitive at chasing money.

There's a bunch of traits in very wealthy self-made people due to the filter they have run through.

Tax too much, and we kill the golden geese of the economy. Examples abound around the world of crappy economies that can't afford good socialist stuff because they've demotivated the rain makers.