Why sell ETH right before ETF open? Why is ETH so correlated to BTC?

As the title says.

I get that ETH and BTC are highly correlated, but BTC ETFs like to dump BTC recently and ETH ETFs haven't started yet so they basically have to be positive buying pressure in the beginning?

While we're at it, why ARE ETH and BTC so correlated? The more I think about it the less sense it makes. BTC miners have to sell the BTC to pay for electricity (most of it by far) and then they have to buy mining hardware constantly with the rest to stay competitive. All of that requires SELLING BTC to increase revenues. ETH staking means you have to hold to earn, and you don't have the huge electricity and hardware costs so you don't need to sell to operate.

Shouldn't these two coins have extremely different buying/selling pressures? Shouldn't they perform far more differently than they do?

Please help me to understand.