Once ETH goes POS (and now it is inevitable in the next 3-4 months) there may not be a profitable coin for GPU mining for a long long time. BTC may still go up, but not sure of ETH and it's derivatives.I keep it simple. I buy and hold. I don't trade crypto.
If I thought BTC was dying I wouldn't be selling my equipment to buy more BTC.
As to selling my Ampere cards -- I won't be selling them until the next Crypto boom, as they'll be worth more then, than they are now. Just like in 2020 when Crypto mining was unprofitable, Nvidia 1070 cards were selling for $200, but during this 2021 crypto boom they went back up to $400-$600 used.
My 3080 FHR card is probably worth $750 right now, but if I hold it till the next boom I can probably get $1000 or more, even if it's another year out, and not currrent top gen. So I should mine with it, until that point, and then sell it and begin to replace it with 4xxx series nvidia cards - since I think Crypto is going up in value - covering my current electricity costs now, and keep the cards - because they'll be worth more in the next boom. Double win. (my prediction)