This is a more plausible story. There is only one electricity bill for $ 2,500, so this is a whole crypto farm. I have no idea how much money should be spent on such equipment. I believed that they started mining on an old gaming computer.
If you do understand the mining business.
You're likely to look at those mining equipment and will be willing to buy as much as you can. As they've started with old pc, they've understood the importance of equipment.
And that's why they're earning this much because they've invested a lot on mining, on the equipment.