> Others dropping out increases your total income because you get to mine at low difficulty for longer

But not if they only drop out when the difficulty swings high and rejoin when it swings low.

Thanks for digging up the original quote and clarifying what I was replying to. Agreed, income per hour indeed doesn’t depend on competition until the next adjustment.

The grandparent was talking about blocks mined per hour, and I was thinking of blocks mined per difficulty period (I guess because I didn't properly read the grandparent's post).

Given that the difficulty period is variable, and becomes shorter when more hashing power comes online, the amount of blocks you'll mine for the current difficulty period does decrease, even if the amount of blocks you mine per hour stays the same.