That is a question which also has the answer in itself if you look at the data,miners made a lot of money in such times and they,the winners did not start mining when crypto reached these new all time highs,they were mining a whole long before this happened.In this time the "losers" started to appear in the market making the prices of video cards skyrocket to never seen before levels and by "losers" I mean the people who came in after they saw the new all time high and they were in for a quick buck.It is exactly these persons who lost the more and sold everything they bought at a loss because mining is not for a quick buck but is a long process that in the end rewards the patient ones who believe firmly in the future of crypto.
The big drops in coin prices taught miners to sell their coins, so few miners kept their coins until 2017. But buying graphics cards during a coin price all-time high is not as painful as buying a coin at a high price and then selling it at a big discount.