I do absolutely agree that extrapolating population over more than a few decades is basically a cointoss, but I still thank that exponential growth is far from certain: Basically every industrialized nation has negative population growth when excluding immigrants right now, and this is very much a global trend.

I like your optimism and would love to see colonies in space, but I think it is overly tempting to consider settling space akin to European colonization of America, when it is more similar to settling on the high seas/Antarctica (right now)-- technically feasible for decades or even centuries, but not really happening simply because of lacking incentives (and the incentive structure looks sadly even worse for settling in space than either of those to me).