While I’m not sure how old these ones, older bitcoin ASICS are indeed only profitable on stolen power. If it produces 1c worth of magical internet money per kWh, then it has only illegal uses.
If you have solar power, you sometimes generate more electricity than you use. You can sell that power to the local power distributor, or store it in a battery. Both have efficiency loss issues (you may only get wholesale from the power company, and batteries wear out). Or you can use that excess power to generate cryptocurrency, and use that to buy more power from the utility provider when you need.
Where are you getting this from? Are you saying the majority of bitcoin mining operations around the world operates on stolen electricity?