"Layer count depends on projected bandwidth & compute, both rising rapidly, which means single layer network [e.g. Bitcoin alone] can carry all human transactions in future imo," Musk said.
That was from 2021.
Discussion
Sorry this was the quote...
“Bitcoin hashing (aka mining) energy usage is starting to exceed that of medium-sized countries. Almost impossible for small hashers to succeed without those massive economies of scale. For now, Lightning is needed,”