Cryptocurrency mining increase by 33 percent last year and as per study it will increase more in future as more and more people getting knowledge about bitcoin mining.
As miners increase difficulty to mine bitcoin also increase. In Jan 2019 it was estimated that 80 percent of bitcoin is already mine. In this case the remaining 20 percent coins are way too difficult to mine.
After that biggest price drop in bitcoin market made miners to quit bitcoin mining and start some other coin to mine.
The price coming from 16,000 $ to 3,500 $ and now again the price increase to 7,000 $
Unfortunately that happen too late that no new miners are coming to mine bitcoin anymore as they are stick to these new coins as they are more profitable as compare to bitcoin.