We'll have to deal with it in some way. UBI, extending production, shifting focus from competition to cooperation can all be done gradually.
Population growth at this point is a result of extended lifespans, due to far fewer people dying of disease, infection, famine, and war. In all but a handful of nations (like Afghanistan and South Sudan), birth rates are down to replacement levels or below, or will be there within a generation.
And declines in birth rates are a consequence of poverty reduction. In the late 1990s, the global extreme poverty rate (less than $1.80/day in today's dollars) was 29%. Twenty years later, it's less than 9%. Astounding!
Get people out of poverty, and the birth rate problem fixes itself in a generation. Which is exactly what happened to the "first world" nations, if you think about it. In the 19th century, Sweden had a 90% illiteracy rate, and was so poor and hungry that fully 20% of the population emigrated to North America. Today, they're... Sweden. The gold standard of modern civilization. Why can't, say, Yemen accomplish the same thing?
True, but the structures we have are mathematically unsustainable. Eventually, it has to become something else. When that shift happens, it's going to hurt.
I think it's better if that change is more gradual rather than a sudden collapse. A gradual reduction of population would be an excellent way to accomplish that.