Career earnings is the correct term for the value displayed, career profit/loss is an entirely different matter, as you point out.
I have a lot of earnings and I'm above a load of players who are way better than me. I am in the fortunate position that I can play more than most of them.
I am the equivalent of the donkeys on Blackpool beach, I grind away to make up the earnings.
The very best players are like a real estate salesman/woman who does 5 hours a week but always comes in with the big money sale. These players are the ones with the high profits per tournament entered.
If people are looking at career earnings as a means of seeing which players are the best, it certainly is a way of doing so. However it most definitely doesn't tell the full story and there are some anomalies in the table.