Wait, you're talking about a channel that has episodes about how to build a Dyson sphere and move the friggin SUN and you're complaining that they did one pointing out that for now we probably can't make things so awful that we'd destroy ourselves rather than maybe get a chance to do these things?

It doesn't ignore climate change--it's just not a central issue to recovering from collapse of civilization. (It might cause a collapse of civilization, but even then it's not as likely as the two things they spend most of their time on.)

You seem very upset that they don't spend their time on social justice issues instead of wondering whether humanity will go on to do huge amazing things or end up destroying itself. The point of bringing up the Romans was not to evaluate the moral shortcomings of their culture. It was to point out that despite apparent heights of achievement, you can fall. You blame them for mentioning that we do in actual fact have an unprecedented level of comfort and abundance without I guess also criticizing us for doing a pretty atrocious job at sharing the comfort and abundance globally (but this is totally irrelevant to whether we survive a collapse of civilization--the point is to talk up how invincible and amazing everything seems when you are among the lucky ones).

And so your criticism goes--they didn't choose to focus on the issues that motivate you, so it's bad. Indeed, it seems like you are so upset by this that at the end you don't even manage to properly characterize their arguments: the "mitigate the risks" thing wasn't even about climate change.

That you have apparently succumbed to climate alarmism and defeatism doesn't help anything, of course; this, I guess, makes you nearly certain that civilization will collapse because of that. The risk is significant; we shouldn't take it lightly. But even if we can't avoid significant warming we can still mitigate the risks of collapse.

It seems like you've just decided that Kurzgesagt is your enemy, and you're going to attack, kind of regardless of whether you can actually back up what you say considerably better than they can.