Are there people who are making consistent profit from "prop firms"?

Yes, some people absolutely do but you got to play the odds. I cycle out prop firm accounts, if one has gained 1% then that account is no longer used for the month to guarantee me profits (and keep me off the radar). I risk 0.1% per trade; yes, ZERO point one. Will I make less profits per account? Absolutely. But my risk of ruin is as close to zero as anyone's going to get. Then through using multiple accounts I can get the percentage gains I want, rather than everyone else who just risks it all on a single account.