Understatement of the century. Look at an AMD price chart for the past few years. Better yet, look at NVDA! Obviously, cryptocurrency mining materially impacted the sector on the way up -- sales growth has been phenomenal, with resellers consistently cleaning out GPU manufacturers as soon as cards hit the market.
If the market takes a dive, we should expect to see that demand dry up. NVDA looks like a bubble chart, much like BTC in 2013. Investors should be careful not to get too complacent with their paper profits.
It's not necessarily 100% caused by cryptocurrency mining, there are a lot of other factors that have boosted both companies: PC gaming became more popular in recent years, GPU's are used for machine learning, neural networks, data science and in other fields, AMD had released a new generation of CPU's. I remember that in last year they were saying that they dont focus on mining in long term, because cryptocurrencies are too risky, and in retrospective I don't think they were wrong, even if they missed out on some big profits, because altcoins can still crash, as most of them are totally useless, and with this crash the demand for GPU's will drop too.