Everyone is gonna give you advise on finishing and tenacity.

Have you thought of the opposite viewpoint - that it seemed like a promising idea, but once you fleshed it out you found out there's reasons why no one else is doing it?

I'd say you're doing it exactly right, keep working on projects, find out if they're dead ends or not, then move onto the next one.

If you want to improve your process, make sure you focus on prototyping and UI, and not worry about stuff like scaling.

Also - opensource your half-done projects on github, so you can have them as resume pieces.