And once your there now what?
Make more UU matter by making more ways to make more UU matter. Then start making higher-tier stuff, and get onto exploring the end with a frameship, then finish my Twilight Forest maze spawn farm. Maybe try and make a wither skeleton farm before the soul shard update to get some wither skulls. And then start working on my sky castle as I'll have enough UU matter to start making iridium reinforced stone.
You have little reason to ever leave your base again all you need is time as once you have some sort of power system and scrape creation that does not require input you got all the everything you will ever need.
You are correct, although the amount of time needed to get to that point is NOT trivial at all. But if it is your ONLY goal, yes, you are going to have an experience that is not anywhere near what I'd like. I only set up my mattfab because I filled up my solar platform with advanced panels, and I wanted to make sure to have enough power on hand for my fusion reactors. The fact that I didn't have a reason to need a fusion reactor at the time, but was still planning on building one should just go to show how I play/think.