For greed! This has nothing to do with network security.
This is guys who even if the sat was worth $1000, would say that the minimum value of a transaction should be 1 sat.

Hopefully I mine a block and earn $200 in my wallet. That $200 alone will cover the energy used to mine the block (maybe it's even too much).

But, if you want, I can give you my BTC address, and transfer all the fees to me, for transactions below 1sat/vb.