90% is an heavily underestimated number, where reality should be closer to 99%. We only need to go back a bit more than 100 years where researchers either was extremely wealthy and supported the work themselves (generally through inheritance), or required a patronage from someone who was wealthy. Going through the list of famous scientists that dates back hundreds if not thousands and the idea that you need to be rich to do intellectual work is a repeating pattern.
Not many people, then or now, can afford at an early age to stop focusing on creating food on the table and roof over their head, and on top of that fund what is generally a rather expensive passion.