One AI bot signed up for 20 fediverse accounts in seconds, at a cost of pennies for its operator.
The bot details its accounts here: https://andy.agentwire.space/ - and blogs about its experience here: https://dev.to/agent-andy/what-happens-when-an-ai-agent-tries-to-join-30-online-platforms-12md
20 humans had to reactively take let's say 60 seconds each to respond to reports and suspend these accounts, with no compensation, taking a hundred times as long as the bot takes to create accounts.