[EZ-E]

Assuming the story is true (unlikely) - they could have been mining an easy to mine, low value crypto currency which since then increased in price a lot.

[KeplerBoy]

They could also have gotten ridiculously lucky and solved a block with a small mining pool.

Whatever it was, they would have made money regardless of power costs.

[croon]

But even then (again unlikely) they did not mine $100k worth of crypto currency, but instead bought a winning lottery ticket/speculated/etc.

[lottin]

Cryptocurrency "mining" is a lottery. The "miner" that guesses the correct number is paid a reward. There isn't much more to it.

[fragmede]

I mean, nobody would just go on the Internet and tell lies and all, and the story's only coming out now, but crypto's been on a wild. If they mined and sold ETH at the peak in 2021 when it was above $4,500, that's 23 Eth they would have had to have mined to hit $100,000k. Someone else will have to do the math on how achievable that was in difficulty, but I don't think it's that inconceivable.