Whereas if you're half-competent and at a startup, the AI is an incredible opportunity to try to leap ahead while the prices are subsidized (by the big tech behemoths fighting wth each other)

The reason is a complete inversion of Ownership and Agency.

For a decade of ZIRP, big tech convinced its employees that they're "changing the world", and what we did mattered. Sure the exhorbitant salaries and constantly rising stock value didn't hurt, but honestly other than the FIRE cultists, for most of us the difference between 200k/year and 800k/year didn't feel much day to day (other than the ability to buy a house or something, and feel safe with a retirement nest egg). No, most people were missionaries not mercanaries.

2021 was the first crack. The comps went crazy, half the industry turned over, and the ones who didn't felt a bitter sting where it became blatantly clear that all the new arrivals were just in it for the $$$, and the companies were willing to pay for the backfills but not to reward the loyalty of the missionaries.

Then came the yearly layoffs, chipping away further, and reminding every employee that they're at the mercy of a spreadsheet and the whims of people 3 levels above them in the org chart, in spite of the economic reality of their product, or their personal productivity.

And now we're here, and it's clear that all of the above is still relevant. The old-timers that hung around see that their personal output doesn't matter, their product's PnL doesn't matter. All that matters is 1) the company's AI strategy (and if they're not part of it, they're secondary), and 2) tokenmaxing.

How can anyone find joy in this environment unless they're purely in it for the comp?

I couldn't. I left my big tech job in December after 15 years, and have not been this happy at work since pre-COVID.