In 2020, I got serious about my YouTube channel after seeing explosive growth from a series on the Turing Pi Raspberry Pi cluster. Early in 2021, the success of my books and the YouTube channel resulted in me quitting my last paid consulting gig, and focusing all my time on Hosted Apache Solr, writing, and making videos.
In 2021 the channel went from just under 100,000 subscribers to 253,000 (and counting!):
Video views went from about 6 million to 21 million, as a few of my Raspberry Pi-related videos took off (though I wouldn't consider any of my videos 'viral'—most get a slow 'wave' of growth if they get popular).