Publishing a game on Steam is not free. So you won't be able to recoup the costs of it since it's free, and making it paid for this purpose is pointless since it's free, lol. You'll need to spend a lot of time and effort refining it to make it worth the $100. And if not, what's stopping you use itch.io?
Viewing post in Should I turn my game into a steam release?
I know it’s not free and I would be prepared to pay the $100. I would spend a lot of extra time making a full game with lots of extra gameplay. The reason I would choose steam is because it’s a more popular platform than itch (Most people don’t know about itch), so less people would play my game if I just chose itch.
I'd use YouTube and other methods to promote. I've read about itch and I don't think it's the best platform for full visibility, although if I finish it properly it will be uploaded to itch.
If you really don't think steam is a good fit, that's okay, I'm not going to critique your opinion of steam. What I might ask is—on any platform, is the core idea good enough for a full game release with several more months of work?