Every (startup) project I've ever abandoned I've eventually regretted abandoning, over the course of my life 5 times if I'm counting right, things like "there actually was a market for that", "with what I know now [insert limitation here] wouldn't have mattered", "thing I did for someone else instead of X eventually bore no fruit but I never went back to X" etc etc etc, going all the way back to the first one in 8th/9th grade where I spent two years working on a product and gave up when I only had one sale two weeks after launch (just needed time to gain momentum, there was lots of demand but I wouldn't realize this until many years later, at which point that whole vertical wasn't really a thing anymore and it was way too late).

Github projects on the other hand, some of mine I'm definitely fine with them rotting, like my crystal lang ORM for monogo db.