One thing that strikes me about the idea of colonising the galaxy is it has practically no economic benefit to the people making that investment. Not to mention

One thing that strikes me about the idea of colonising the galaxy is it has practically no economic benefit to the people making that investment. Not to mention that any society you set up on a neighbor star is likely to diverge culturally (and perhaps biologically) in significant ways — perhaps to a point where they’re more likely to be mysterious rivals rather than friends.