That insecurity can be lethal because it's not just about the paycheck and health insurance; we define ourselves by labor. It's the first question we get asked by strangers, it's the first thing mentioned in any news story about us ("Local Elementary School Teacher Arrested After Nude Food Fight At Country Kitchen Buffet"). Even if we take long breaks in the stockroom and are just biding time until we can use the copier to make our sweet zine, we still spend half of our waking hours at the workplace. It's likely where we have most of our social connections. And it can all be yanked away at any moment.
And if you're working in the gig economy, it's even more tenuous -- Uber doesn't have to fire you, they just "deactivate" your account. "You weren't fired", it implies, "you never worked for us at all."