Just to be clear, this is different to the problem of Google ads that link to malware and fake banking websites and promotion of cryptocurrency scams isn't it?
In the ad marketplace there are four participants: the advertiser, the user, the network (Google), and the publisher (also Google for AdWords, other websites for AdSense and so on, and effectively the channel owner for YouTube).
In the click spam or botnet case, the bad actor is the user, who is usually associated with a publisher trying to get extra money (although not always - there's reasons like auction manipulation where some advertisers run click bots too). In the bad-ads case, the bad actor is the advertiser.
At Google, each of those problems has their own well funded team, but they do also share some data to help catch rings of bad guys.