Miners may not be paying what we pay for electricity. For example, the flared gas miners in Texas. Since they reduce methane getting released, natgas producers save money on emission penalties. Theoretically, it would still be worth it to let them mine off the flared methane, even for free. There may be many more of these types of situations where power may be sold to miners for pennies on the dollar.

Miners will mine at a loss sometimes if they think they can put others out of buisiness. Also, if they have the money to not sell their Bitcoin now, they are not intending on selling Bitcoin at these current prices. This could mean that miners are expecting the price to go up before they burn through their cushion.

Another contributing factor is that every year, the ASICs themselves get more efficient. Miners can be using the same amount of power they did 2 years ago, but with slowly replacing older ASICS with newer, difficulty will continue to rise.