There are a few folks who actually manage to successfully be "professional" gamemasters and charge for their services. Not a lot, but a few who have found a niche to fill. Doesn't affect the hobby negatively at all, or somehow make "normal" games GM'd at no cost more difficult to find. Most GM's don't charge, in fact, couldn't get away with it, but the few who do don't demean or damage the hobby. Under the right circumstances, charging for your GM services isn't morally bankrupt or anything.
If my pal who DM's our weekly D&D game session (we're all friends) decided to start charging . . . I'd tell him to get stuffed. If I didn't have a group of friends to play with, had the disposable income, and found a "pro" GM willing to add me as a client . . . I might do that.
Most FLGS don't charge for playspace, but increasingly more are . . . because real estate is expensive. I appreciate my FLGS for providing a large, well-aired, clean playspace at no charge . . . but if they decided they had to start charging I would totally understand. I wouldn't be comfortable paying to play in a specific game, but I wouldn't mind a "cover charge" for using the playspace in general. Especially if that cover charge came with a equal value coupon towards merchandise purchased that same day! What my FLGS would do with that money doesn't concern me . . . pay the mortgage, pay GMs or referee's, etc. As long as I felt the value was there versus the cost, I'd be okay.