Well I haven't really joined bounties before so I have no idea how much people earn. Soforex would paid in bitcoin if they managed to raise enough for their ICO but if not, then I'll end up with tokens and finally experience it.
If based on current bitcoin price, yes we have millionaires here in their respective fiat currencies (not USD) especially if that coin really pumped hard. Also it's not that they will just joined single project since there are lots. No need to take on multiple accounts just to reached that but honestly others are doing that although it's time consuming.
There are users here who have been in a bounty for long time so I guess they make more money now although it's needs time.
Are those really that profitable? I mean, I just have this account of mine and I had it joined a sig campaign before. I went for almost a month without one since there don't seem to be much open.
But yeah, I agree with the fiat millionaire in currencies aside from USD/Euro. A million in my currency is just around $20000 and people who spend a lot of time here probably can earn that.