dont make acusation like that, anything breaks when put under a certain amount of pressure or abuse.
Ofcourse everything can break, but honestly, show me a picture of a broken 20mm. Ask the guys at ur LBS, they will tell you it takes alot of shit to bust a 20mm axle.
i will show you a picture of a broken 20mm axel. give me a couple days to get it
IF you switch from 10mm to 20mm you need to change everything to do with your wheel (including your brake adapter if you have one) I forgot to do this and it didn't turn out very good.