Are layer 2s essential to Ethereum’s success?

What impresses me about ETH, is that it's being used for the majority of decentralized financial transactions. This became clearer to me after minting my free reddit NFT avatar and learning the process of selling it requires gas fees to transfer the NFT. I need a balance of ETH in my wallet at all times as the currency. I had the realization of just how high volume and high demand these types of markets are operating in. They're cooler than I expected!

With that said, to keep the growth trajectory while maintaining security and fees – an endless number of second layer chains can attempt to evolve with Ethereum for a better user experience and ecosystem. It seems there is a natural competitive environment for L2s that lead to a survival of the fittest, best solution wins. Does that mean ETH can continue to improve forever? Is this reason to believe supposed "ETH Killers" are not truly a threat?