Each year, Bitcoin produces ~37 megatonnes of CO2 per year (https://www.downtoearth.org.in/blog/environment/as-cryptocur...), and i won't consider any other cryptocurrency.
Now, let's assume for a moment that every single youtube video is a cat video, since i found nothing about how much people watch these. So 10 megatonnes of CO2 per year (https://www.wired.co.uk/article/youtube-digital-waste-intera...).
Obviously this is very unfair to cats. But even if that were the case, with this calculation being _really_ biased for crypto, it's still very bad.