It's possible to make money but it's not guaranteed (Just like any other site). The reason why i like it is because: It's free. It's reasonable and easy to use. You're in charge of your own destiny, pricing, etc. You're forced to upload quality. Put together a maling list for buyers and potential buyers. Payments go straight to your paypal. It's really a well thought out blueprint for the artist. Its nothing like soundclick and not quite like a networking site where fake ass niggas dwell on some "WhaTup FaM leTs CoLlab chEck out me beAts fiRst" type of shit.
If you're talking about those Rocbattle sites where you lease a beat for $25 and all that other hooplah? Those sites are done. I dont fuck with em. shit just seems so cookie cutter and biased to me. Lost in the Bermuda Triangle abyss of copy cats that have no original style and just do whatever is hot at the moment. (rant over lol)
But yeah man, check it out and Im sure there is a lot of other sites out there. Another good site is soundcloud...just research. peace