Why do you consider rock-paper-scissors a skill game?
It is mainly luck based IMO, though if it is played face to face, you may be able to read your opponent's gesture and predict his movement.
Because if you play hundreds of games, a skilled player player can reliably hold an advantage over a less skilled player -- by reasoning what are thinking based on the move history. I have a friend who I played a couple thousand games with online, (iteratively) and he was able to consistently beat me ~35 to ~40% of the time.
But anyway, the same applies to lots of skill games that involve exploiting human weakness, and where a perfect bot will make no money.
When I think about skill games, I immediately think of games like chess and backgammon, which people have created extremely powerful bots...
Yeah, those games are really hard to gamble with -- even if it's not for bots, it's for the difference in peoples skills, people pretending to be worse than they are (losing to their own shill accounts if needbe), and winning high stake games etc.