Uhm. I said, I do not understand why some developers release their games as paid with no demo version.
If there is a good reason to do so, I would be curious to hear it. (And then explain why the reason is not good at all ;-)
You do not need to give away your games or switch to pay what you want, but consider having a demo version. You just cannot try out a game that is paid with no demo. Downloading a demo is a smaller hurdle than paying for an unknown game from an unknown developer. An even smaller hurdle is having a html5 version of the paid game. A rather popular example would be Backpack Hero. You can play it as a webgame, despite the game being paid only. It is an older version, but you still can try out the game concept without payment.