Do you know why it is difficult for BTC's second layer to grow?

One of the core reasons is liquidity. Most of BTC's liquidity is in the hands of BTC OG, exchanges, and institutions. They will not exchange real BTC for fake BTC. This group of people has a deep understanding. You want to just come up with an EVM second layer and cheat their BTC away, but that doesn't exist. It can only attract retail investors to play, but retail investors have fewer chips.

On the other hand, ETH and SOL, the giant whales of ETH and SOL will really play on their chains, so there is sufficient liquidity.