With D-D fusion it might be possible to "live off the land" between the stars which probably have numerous interstellar objects of various sizes between them with a much larger cumulative mass than planets orbiting stars -- and it may be possible to completely disassemble those kind of bodies which are much richer overall in carbon, hydrogen, oxygen and nitrogen than terrestrial planets.

A species with that kind of capability would be able to visit another solar system in 10,000 or so years but might care less to mess around with dry little solar system bodies like the Earth. The case against "grabby" aliens is that Ceres and Pluto are still here, not that we can't find evidence of them on Earth.

I like to imagine that if that kind of interstellar traveler were to visit Earth it might take them a few decades to perfect a "reverse space-shuttle" because they'd gone 10,000 years without doing anything like that... And they can't just 3-d print one out of 10,000 year old plans because they've improved their 3-d printers to print the stuff they've been printing all that time better.