In my opinion, mining with high powered hardware is a fool's errand. You have to have a lot of money to buy a lot of powerful hardware to earn anything. And then you're spending a lot of your earnings on cooling/electricity, hardware maintenance, or just buying more powerful hardware to keep up with the ever-increasing hashrate. I have a hard time imagining that your mining hardware isn't practically obsolete if you've had it for a couple of years. In my opinion, the competition in Proof of Work (PoW) chains is too fierce to earn anything worthwhile unless you're already very rich or you just get very lucky on an up-and-coming coin that (1) is dirt cheap and/or easy to mine when you first discover it, (2) increases significantly in value, and (3) doesn't totally tank and lose most/all value (at least before you sell and get rich off of it).
It may be worth looking into Proof of Stake (PoS) chains, where you don't need (very) powerful hardware. Rather, the number of coins you have staked act similar to raffle tickets entered into a pot from which you can randomly be chosen to process a block and earn rewards from it. But because there's no rush or competition for the work, you don't need super powerful/expensive hardware running at full speed 24/7. I haven't been paying close attention to Ethereum (or much of any crypto) this year, but last I heard, they were trying/planning to migrate their chain away from PoW to PoS.
Alternatively, instead of doing the mining yourself, some PoS chains have something similar to a mining pool, in which you can delegate your coins to a miner or a pool which will make regular payments to you every few days from the earnings they get using your stake. Minus their fee, of course. Keep in mind that your coins are always under your own control (if the blockchain is doing it right). You're only delegating your voting/staking/mining rights to someone else, not transferring your coins to them. That way you don't really have to do any of the work but you can still earn a little something extra along the way. There can be a bit of a waiting period while you wait for your first payment after you delegate, but after that it can be fun to see little payments going into your account every few days.
As for cryptocurrencies that will be long-lived, here are a few that seem likely to be around for a while, in my opinion:
Bitcoin ("blockchain 1.0")
Ethereum (touted as being "blockchain 2.0")
Cardano and/or Tezos (touted as being "blockchain 3.0")
BTC is obviously a PoW coin, and I believe that ETH is still PoW for now. Cardano (ADA) has just launched PoS on their mainnet in the past day or so, and Tezos (XTZ) has been running their PoS blockchain since their mainnet launched two years ago.
There are others that I like or that interest me, but these are probably my top picks for what I think will be around in some form or another in the long term.
Full disclosure: I own or have owned a little of all four of these.
And of course, be warned: Do your own research and never spend/invest more than you can afford to lose.