When people say that they "mine Bitcoin" what this actually means is that the protocol will show them a number on the screen once they solve a hash combination. Literally, they spend energy to get just numbers on the screen. Number that count nothing. It's crazy how dumb this is.
there's even more madness to the story if one is willing to hear it all. once they get the numbers on their screen, they sell those numbers to someone else. so they can get real money...

so as soon as they get it they want to get rid of it, many of them do. how does that make any sense?
It makes sense because they know very well that numbers on the screen is all they have. But as long as there are enough suckers that want to buy them because they believe that numbers count some magic coins, they'll keep spending energy to get them. It all boils down to ignorance and greed. People are generally ignorant what money is. And they saw others "profiting off of Bitcoin" so they just want to get in, no matter what. That's why you can sell the digit "1" for $70K or two digits for $1M. It's literal madness.