Ethereum and Solana work together in this space.

Why is everything a "ETH killer" to everyone?. Many blockchains will shine in different fields that the others will not. There will never be a coin that will rule them all, a competitive free market will have different options available for people.

Ethereum has the most TVL and tons of apps so it's not going anywhere. Solana is focusing on simplicity for the average user by offering cheap fees and fast transactions. It's investing heavily in gaming/web 3.0 and NFT's.

Nothing is stopping you from diversifying your portfolio e.g. 80% of ETH and then the rest.