Well, you need to understand what opportunity cost is.
Let say they are using 1 MWh of power continuously 24/7 to do all sort of mining.
That power can be used at where else, maybe powering a factory and provide more job opportunity or EV charging service or other more useful activity.

Then, you also need to know what indirect cost is.
There is a lot of indirect cost incurred to do this sort of mining.
Electricity Company like TNB might need to build more power plant just to cater mining activity.
And this activity does generate lots of heat.
Then, maybe one day they decided to quit this business or rug pull entirely (very likely to happen), someone is going to bear the cost.