the network can't hope to handle the number transactions per minute that Bitcoin does.
As of this writing, Ethereum is handling 21.1 transactions per second. Bitcoin is handling 4.9 transactions per second. So purely in layer-1 transactions per second Ethereum's got 4.3 times the capacity of Bitcoin.
Some of those Ethereum transactions are for running layer-2s, as you mention that greatly expands Ethereum's capacity. Ethereum is specifically designed to be able to handle layer-2s well, it has features that were added to make them easier to scale. Bitcoin, on the other hand, was never designed for layer-2s and what it does have are hacked-together bodges like Lightning that are going nowhere.
I think most people agree that the two systems compliment each other, they each work well in their niche, but couldn't do the others' job.
What "job" does Bitcoin do that Ethereum can't? And before you say "digital gold", there are literal gold-backed stabletokens on Ethereum if that's what suits your fancy.