Once you have any way of allowing other people to use cycles... They will do it. And you can't really be surprised when you have these cryptocurrencies that folks in need of cash with few if any other options use it. It's why I object to the activity on principle. It becomes the new default+ activity. Any computation not explicitly provisioned in a way that guarantees pre-empting a cryptocurrency generating process n…
Yes, this needs to be solved at the crypto level - attackers always have the advantage.
Monero is quite hard to trade directly to actual money - you usually have to go via BTC or ETH.
So a systemic fix basically involves crashing the price of crypto in general, to take away the financial motivation.
(This is also one obvious solution to bitcoin's CO2 production - it's all about the US dollars, so hit those gateways.)