It’s certainly a personal preference.
I experienced exactly what you meant on my first run. Launched a rocket after a lot of slog, and lost interest after that. But I never got to actually use eg the nuclear tech very much, which itself makes me want to go back and try it again.
Personally, I wish there were more combat/enemy dynamics involved rather than “just” insectoids swarming the base. And that’s just one angle: other compelling reasons to build more efficient factories would have made me want to go back too.
I try every now and then to start from scratch, but just the idea of starting from the basics seems so daunting and not motivating enough so I kinda just give up after the first day.