On December 14th, 2018 YouTube deleted every account that they deemed “spam.” This was done to combat fake users, and inflated subscriber numbers.
This table shows the subscriber counts of the Top Crypto & Blockchain channels before and after the December 14th, YouTube Purge.
SocialBook.io is an influencer discovery tool where you can find your influencers by using keywords and see their channel performance, engagement rate, past brand mentions, and audience demographics. Here is a sample profile for your reference.