High gas fees, reduced popularity of DEFI, rapid decline of TVL on the chain, distrust of ETH2.0, criticism from miners, and restrictions on participants by the POS mechanism. Will the challenges of new technologies and new public chains cause ETH to decline rapidly?
Bitcoin has the highest fee, yet remain the most valuable cryptocurrency, ethereum remain the second ranked cryptocurrency after bitcoin and has the second highest fee. Reduced popularity in DeFi How? Ethereum blockchain has most numerous DeFi tokens. With everything you have said, there are ethereum killers for years now, but ethereum remain valuable and the strongest of them all.
The fact that they have the highest transaction fee is because they are at the top, not the other way around. Meaning, people use these two so much that they are willing to pay premium to keep using these two, they are so much so willing that they are spent 30+ dollars on each transaction at one point in time, instead of using stuff that had zero, so they lost 30+ bucks on each transaction at least, and they still didn't switched to other stuff, some people did but many didn't. That is the reason why we should not be really shocked that these two are at the top of the chain. Because, they are loved and people are willing to use them a lot.