https://www.pcgamer.com/cryptocurrency-miners-bought-3-million-graphics-cards-worth-776-million-in-2017/

Last year was a big one for cryptocurrency mining, and it culminated with a shortage of graphics cards and grossly inflated prices. According to a new report by Jon Peddie Research (JPR), miners purchased over 3 million add-in board (AIB) graphics cards worth around $776 million in 2017, with AMD emerging as the primary benefactor of those sales.

Those numbers are actually lower than we would have guessed them to be, though obviously still high enough to have a major impact on the market as a whole. If there's a silver lining for gamers, it's that gaming is the still the biggest market for GPUs.