What do we know about left wingers in general? We know that they usually don't have children or if they do they only have one or two and those children often have problems. We know that their marriages don't last. We know that they're gradually getting stupider as their ideology takes over from their ability to reason or justify their points. We know that they're usually emotional basket cases. We know they're impractical and short term in their thinking, have to be frequently bailed out by others and don't plan ahead or effectively build. Specifically we know that they're phenomenally self destructive, have little impulse control, live in the moment, and surrender to their sensations to their detriment. As was pointed out Lynne Featherstone demonstrates all of these characteristics.
In short with all of these traits over the long term they're stuffed. They in elements have the hallmarks of a fever that has to be sweated out. You just have to stay in the game till its passed and people's desire to survive and grow, not just live off the strong accomplishments of the past, can kick in again.
Virtually all of left and liberal wing thinking relies on the assumption of the Western European world being rich, prosperous and on top, and as this comes into doubt the self indulgent destruction of the left and individual indulgence of the liberals will be called out for what it is. You can only get away with blaming others for so long before people stop listening and so much of the left liberal movement relies on the public's tacit support. You can also only shoot yourself in the foot so many times before you lose credibility.
Obviously there are individual leftists who are not like this in their personalities. But taken as a whole, liberal society does give this impression - that there is little serious consideration given to what is sustainable in the long-run; that many individuals prefer to feed their emotions with a self-indulgent sense of moral rectitude; and that the capacity to take hard-won gains from the past and to preserve them simply isn't there.
And although I would not recommend waiting for liberalism to self-destruct (as there is an institutional basis to liberalism that can keep it going if left unchallenged), nonetheless part of what we have to do is to try to outlast it. We have to do what we can to keep reasserting and reproducing what liberalism attempts to suppress or abolish.
Finally, it's not impossible that there will be a tipping point at which liberalism's claims will no longer be so widely accepted. If, for instance, China continues to rise and to dominate parts of the globe, then left-liberal explanations of inequality that involve whites being a uniquely evil and artificial oppressor group will be harder to swallow.