Because everything that has made life worse for millennials, is not fixed, not even a little bit, and is not going to be fixed. It is going to keep getting worse and it is not clear people are even really trying to fix anything anymore because we are, as the article points out, burned out. There is almost nothing on the horizon that has much potential for making anything any better or easier for anybody, and the few things that do have that potential, like AI and automation, are very clearly (to me) going to be misused for exploiting humans in almost every possible way and making life harder not easier for the vast majority of the human population which likely includes everybody commenting here.

GenZ may instead get burned-out literally -- from their homes, as humanity continues to work mindlessly towards a goal of creating enough heat to set the entire planet on fire, but maybe the rising oceans will put some of the fires out. Families and mental health and the fabric of society will continue to fray. Prices will keep rising. The wealth gap will continue expanding. Lawlessness and homelessness will become rampant. Democracy will continue to slide towards corporate tyranny and fascism, and peace begins to make way for conflict and war.

Time plus exponential decline.

The frequency with which once-in-a-generation calamities are occurring.