I remember why then the miners sold their coins. Nobody believed in the growth of the cryptocurrency price and at any moment you could lose a good profit. I sold ethereum and bought video cards. Banks did not block debit cards, after the exchange I immediately bought components for the mining farm.
When I started to mine LTC/DOGE I was too young to have a bank account or credit card... so I bought Newegg gift cards with BTC then used the gift cards to order PC components, LOL.
The reason miners have never gotten as rich as the buy & HODL folks is because miners are motivated by short-term profit and 'ROI'. However, times are changing. Now that we've had 2 gold rushes and crypto got to the trillion mark, more miners are saving their coins.
RIOT/Whinstone, the biggest miner in the world, might have suffered after the Bitcoins they owned dropped in value, but I think they will be really successful in the long run.