We're not all going to die, but my point stands.
It's not about the earth shifting, it's what happens to all of the human processes, trade, infrastructure, farm production, and human lives along the way.
Imagine a snowball rolling down the mountain that turns into a basketball sized ball, that into a mountain sized ball, that turns into a planet sized ball.
There are numerous periods throughout human history where we have almost gone extinct, and several where we have had under 10,000 people worldwide.
The pandemic demonstrated that the global economy is a finely tuned machine. It doesn't take much to upset the operation of such a beast, and a big interruption could have massive unforseen consequences.
Think about it like a complex, mission critical software system. Are you going to make big changes in many key areas and rush them out to prod? Or do you want to release them individually over time.