I bought 2 GPUs at the beginning of the pandemic to continue my ML work at home. I mined ETH on the downtime. Gained about 10k EURO and easily payed for the GPUs. Then got out right before the crash. For me it has been a fun experiment, but the main drawback of the biggest coin BTC, is the limited amount of transactions.

I am not sure I am right about this, but as the difficulty gets higher, not only do you get fewer rewards (join a pool to make it regular, sure), but at the same time, the amount of transactions that can be put on the ledger is going to slow down over time.

And if you look at the capacity of the BTC blockchain and have a look at the maximum number of supported transactions, it is only a few per second.

Imagine 7 billion people using BTC and only having at most half a million transactions per day. That is not a currency, sorry. It just does not make sense to me anymore. It is a speculative thing and not much else. I have speculated and won. Paid off my GPUs and the electrical energy, but I do not see crypto as a viable alternative anymore.