Proliferation of L2s seems inevitable

It doesn't matter how good high-performance chains like Solana, Sui or Monad. Desire to owning their own chain is inherent to builders and founders

It is not about scaling or security. But what motivates to launch their own chains are sovereignty, dedicated resources and most importantly, value accrual to their brand 

Exceptional cases are applications which heavily depend on the network effect of the underlying chain. For example, DEXs, or most of DeFi protocols, can't leave the chain since the tokens to be traded are located there