Interesting, this is a _feature_ of poker games like Texas Hold'em. If the losing players didn't go on convincing winning streaks, they'd stop playing. And those winning streaks can convince them they don't need to learn anything else about the game in order to be a winning player.
Have you ever gambled over a game of Dominion? I wouldn't.
Have you ever played Hold'em without gambling? I wouldn't either.
Well yeah, there isn't really enough hidden information, and the amount that's there is usually not very interesting (it's pretty rare that you'd change your play depending on whether you think your opponent has a particular reaction card in hand, and there's no real bluffing mechanic i.e. you can't meaningfully manipulate the stakes for being wrong about that).
I guess the game just appeals to a particular personality type that I belong to and not a lot of others do. I guess it sold well enough to people who only played it a few times, though.