They might demonetize some radical channels but they're still making money on users who get to YouTube through those channels.
https://mobile.nytimes.com/2018/03/10/opinion/sunday/youtube...
https://mobile.nytimes.com/2017/11/04/business/media/youtube...
https://news.vice.com/en_us/article/d3w9ja/how-youtubes-algo...