It would be one thing if it were driving more users to my forum. But human usage hasn't changed much, and the bots drop cache hit rate from 70% to 4% because they go so deep into old forum content.
I'd be curious to see a breakdown of what the bots are doing. On demand searches? General data scraping? I ended up blocking them with CF's Bot Blocker toggle, but I'd allow them if it were doing something beneficial for me.
Part of the problem is all those companies who use AWS "standard practice" services, who assume the cost of bandwidth is just what AWS charges, and compute-per-page is just what it is, and don't even optimise those (e.g. S3/EC2/Lambda instead of CloudFront).
I've just compared AWS egress charge against the best I can trivially get at Hetzner (small cloud VMs for bulk serving https cache).
You get an astonishing 392x(!) more HTTPS egress from Hetzner for the same price, or equivalently 392x cheaper for the same amount.
You can comfortably serve 100+ TB/month that way. With 10,000 pages times 1000 bots per month, that gives you 10MB per page, which is more than almost any eCommerce site uses, when you factor that bots (other than very badly coded bots) won't fetch the common resources (JS etc.) repeatedly for each page, only the unique elements (e.g. HTML and per-product images).