Ringworld.

A quote attributed to a few people, Heinlein and Pournelle for two, "If you can get your ship into orbit, you're halfway to anywhere." Both space and planets have shared and their separate problems to solve. In my head I prefer the image of most populations moving into habitats in space, customized to their preferences, with smaller settlements on various bodies for their own purposes. In my realistic view I don't see us getting that far before we get bogged down with all the problems we've created on this planet. The window to a permanent space civilization might have already shut. A sad thing, as a 70s kid I grew up convinced we were full speed into some version of what scifi had sold to me.

We. Like, you and me? Whatever you wanna do I guess.

Both.

Genetically modify ourselves so that we can live both in zero gravity (and maybe survive short exposure to vacuum) and on other planets.

After reading A City on Mars by Kelly and Zach Weinersmith I think a O'Neill Cylinder spinning spaceship for artificial gravity type is more achievable than planarity colonisation.

But the main point of the book, and I am fairly convinced of the more I think about it, is that it is a lot of effort and risk for not a lot of gain and we are entirely unprepared for space colonisation.

Neither. There's plenty of room and resources here on Earth. I think it's fine to do space exploration and even have research bases on moons and other planets, but I just don't see the imperative for colonization.

Actually, both.