Strongest pure amature

while lookin up famous chess nicknames givin to masters for personal reasons  I've noticed that a GM named Helmut Pfleger was called the strongest pure amature since he does not study opening theory and he suppossedly said he never has nor to much the endgame yet he achieved the GM title in his career and I was wondering what others think of this grand master along with him Capablanca has been called the same thing cause of his persistants to not study as much.

Dont forget Max Euwe. 

Strongest player not to take up serious chess as a profession is probably Euwe. He did study theory and write books and the lot though.

Are we using "amateur" to refer to someone who never made a dime from the game, or someone who never used it as their sole means of income?

both

Well, at a certain point chess wasn't considered to be a profession, so most of the old masters were amateurs to a certain extent. In Soviet Union chess was also not treated as an official occupation. It we take modern days, there are some players who have a regular job and a 2500-2600 rating. 2700+ are usually pro.

Euwe was World Amateur Champion. A few years earlier he had barely lost a match to Alekhine 5.5 - 4.5 .......that's a pretty strong amateur 

definitly

?

So an adult who tries hard and plays many decades and even studies a few books can reach class A, but typically to reach Expert, which is not referred to as amature, you need to make it a serious hobbie above many other activites?

 ?

brilliantboy, what is "World Amateur Champion?" 

Euwe won the World Chess Championship against Alekhine by a score of 15.5-14.5 in 1935.

 http://en.wikipedia.org/wiki/World_Amateur_Chess_Championship

Alekhine played a training match with Euwe in 1926/27 as preparation for his World Championship match against Capablanca

Thank you for the history lesson, brilliantboy.  As the article at chessgames.com says, that match was overshadowed by the later world championship matches.