Breakeven calculations for tournament play is fairly straightforward to figure out. Cash games, not so much.
If 10% of tournament field is paid, then only 10% of any given field is getting "some" money back. You would likely need to cash once for every 2.5 tournaments if you are min cashing (43 out of 100 tourneys), in order to just breakeven (considering fees etc.).
Generally only 3-4% of the field pays at least 10x the buyin which would be necessary to breakeven if you were to finish near the top of 1 in 10 tourneys. Many players may finish near the top in a tournament like this but not consistently enough to stay above the breakeven mark.
So.... given this, it is clear that only 1-2% of tournament poker players are winners, if winning is defined as "consistently won more than their buyins".
I have personally cashed in 18% of the live tournaments i have played in, which i think is very good, however, because very few of these are the top spots, i am actually not winning from a total view of the data. I am sure i am just one tournament away from the "big one" however, so I keep playing. LOL.