I like to think that my side projects are primarily
a hobby, which I understand as an important venue for "venting off" after work. Notably, if they start to feel too much like work, they're no longer hobby projects, losing their super important (for me) psychological function! I mean, I still do feel guilt often, and am still on a lookout for some way(s) to cope with it... But interestingly, in my case, for one of the projects, my itch was so strong eventually, and I was so often annoyed I don't have this tool, that it kinda "forced" me to find the strength to push through to the completion, even when it was becoming a chore. Since then, I again abandon projects with guilt repeatedly ;) but again also have one among them, that I'm coming back to on and off, when I feel fancy, and trying to push forward. Again, I'm kinda repeatedly getting annoyed I don't have it for myself; when annoyance of not having it becomes bigger than my memories of annoyance developing it, I'm getting back to it again :) sometimes looking at it reminds me too much and is enough to scare me away again, but sometimes I'm just so angry I say to myself screw everything and sit and push through :) Still, also as others said, I look at the unfinished "hobby" ones also sometimes as some kind of research I wanted to do, thus honing my skills or just randomly "playing with my mental muscles" in various ways anyway - kinda as a kid plays in a sandbox however they want. They don't ask anyone for permission to drop the toy car and start digging a funny hole in the sand, just to fill it back with exactly the same sand moments later.
edit: One more thing from what others wrote that also kinda resonates with me, is that especially with the finished project, I kinda did repeatedly cut corners, and I mean a lot, like freaking brutally, to get to the absolute minimum and absolute most brain-dead simplifications and quick hacks, kinda like taking the machete and just cutting my way through the jungle not looking behind, just to get to the PoC. I cut worlds of ideas from it, leaving them as "TODOs", scribbling in a notebook, or just "mañana-ing" with cruel premeditation, I still hear them howling at me with angry remorse. Uh, sorry folks! Some day, y'know, pinky promise, maybe!... I remember you, I really do (mostly...), but, y'know, kinda different toys now that I'm playing with, y'see... And suddenly, this PoC (wrapped in a pretty readme and asciinema gif, which were actually the most exhausting finish of the whole run... but I was so close, it was like no way, if I don't do this, nobody in the world will know how an awesome tool I made... but they must know... it will help them sooo much... I think... I mean, it helps me so much... and let them just see the gif... gifs are pretty!!) kinda proved to be enough, both to me and to tons of other people I wanted to share with and thought may also like it, and closed my eyes and published, saying screw possible bad reactions or just crickets... sweet! :)