I suppose it depends what the goal is - the question being asked suggests to me you want a successful side project (or even full time business?) no matter what it is, the tech it uses, etc. If that's the case, then I can't speak to motivation, but you need to pick a project based on identifying a niche, product market fit, etc., not experimenting with what's hot and sparking your interest this week.
If that's not right, then I think the question's wrong, and maybe you just need to come to terms with it being ok to experiment with things, prototype things; that they don't have to turn into an MVP that anyone else ever sees, you're just having fun/learning about things.
And even if it's a bit of both, you want the successful business, just only if you love the tech or idea, then you're still doing nothing wrong, because all these so far have not panned out in the loving it sense before they had a chance to pan out or not in the business success sense (so that's inconsequential).