just came across this news and well, I wouldn't invest on 30XX series to mine
https://cointelegraph.com/news/eth-miners-will-have-little-choice-once-ethereum-20-launches-with-pos
"Mining" is not really very profitable for quite some time unless you have access to very cheap electricity. Recently, probably due to the incredible bubble created by the "DeFi" craze, mining Ethereum is quite profitable for a brief moment (arguably it still is, again depending on how cheap your electricity cost is). Buying 3080 to mine Ethereum is unlikely to be able to recoup the cost as it might take several months to cover the cost of the card alone, and Eth 2.0 with PoS could already be out at that time.