Visiting is trivial compared to independently thriving.
Which reasons, as for 99% of everything else like that humans have ever done, will likely be economic or military. When it makes dollar-sense to do it, we'll go. Not sooner. Not really, and not for the long haul.
I'm doubting we'll do large-scale human colonization of space for a long, long time, if ever. We might do mostly-robotic asteroid mining within the next 100 years, and a couple visits to e.g. Mars might be made, but nothing serious.
On a slightly different tangent, The Moon Is a Harsh Mistress [0] suggests that whosoever sets up the lunar catapult first will likely become "masters of Earth". I think I'm going to start learning Chinese! [1]
[0] https://en.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress
[1] https://spectrum.ieee.org/china-aims-for-a-permanent-moon-ba...
Wasn't the same argument made against going to the moon?