When will technology advance to the point where we can live on Mars or the Moon?

Yesterday, @zaczuo shared an idea about delivering packages from space. To me, that seems quite sci-fi and financially demanding to actually pull off. Today, I’m reading that Bezos predicts millions of people could be living in space by 2050.

How realistic is this scenario, given that the last time we set foot on the Moon was more than 50 years ago? (And above all, I feel like we still can’t solve basic problems on Earth, let alone expand into space.)

I believe several people here might be interested in this kind of topic, at the very least, @konrad_sx