Part of the reason for pessimism is that the enormous progress of recent centuries is due to a set of liberal political philosophical ideas that are being rejected by an increasing number of nations.
That implies that if the present political trends continue, then as some point in the coming decades progress for the world as a whole will reverse.
"It only takes 20 years for a liberal to become a conservative without changing a single idea." - Robert Anton Wilson
The idea of there being an right and wrong direction to history is flawed at best.
The current rejection of liberal values didn't come out of nowhere either. Some people are unhappy and feel the system has failed them. This was the same reason that pushed liberal ideas to the forefront in the first place.
Even drugs are not legalized, up until recently homosexual marriage was not recognized. People toil about the same hours, though more often mentally than physically now.
You have no direct choice in how to pick candidates for Senate or presidency - you can only pick from choices presented to you, and even there tribalism of the masses beats any individual choice. (The best you can hope for is picking a governor.)
Where is liberal in that? Where is the liberal, when all rulers are ivy league educated?
In this sense, (and what I believe to be the sense of the original quote) I mean a person who wants to see societal change.
The examples you've provided actually give a pretty good picture of it. A person who was liberal 20 years ago would look at what you've described and wonder what the heck happened. They might also look at the current topics of social reform and probably not recognize themselves in them.
Essentially, anyone who has a teleological view of history tends to get burned within their own lifetime as the world inevitably moves past them. You get "assigned" a set of topics and social struggles from the environment and historical you grow up in. Since the next generations grow up in a different soup, they don't follow the same lines of thought. The person who scoffs at their grandpa for being lukewarm about same-sex marriage becomes the grandpa lukewarm at their grandson's simulated AI life-partner.
>you can only pick from choices presented to you, and even there tribalism of the masses beats any individual choice.
Going off on a tangent here. You are part of the masses. You are not in traffic, you ARE the traffic.
That implies that if the present political trends continue, then as some point in the coming decades progress for the world as a whole will reverse.