Certainly if they're like us, and travelling to new worlds, they'll be imperialistic and colonial. They'll plant a flag, because we obviously weren't really making use of the planet, not _really_, and attempt to civilise the natives through something between cultural erasure and genocide.

On Earth, in the grand scheme of things, it took a very short time for colonies to a) diverge politically or b) fail. It's not something that stopped happening (much) because we became more cuddly. It's just boring old economics.

So I think it's unfeasible to maintain a society that rules with an iron fist over interstellar distance and time.

Colonialism isn't profitable for the same reason slavery isn't. We did it because we hadn't invented economics yet.

In space it seems like it'd be even worse; something would have to be very valuable to be worth taking it out of our gravity well.