It's up there but not singularly so. Twice there have been $10M! You can see the leaderboard where the majority of crypto bounties are represented here (https://immunefi.com/leaderboard/) but you have to search around for the actual reports.
nope, not at all! the crypto sector has been the most lucrative thing you can be doing in software for a decade straight now, especially with the lowest CapEx - AI doesn't even come close when factoring that in - bug bounties have been larger and only a subset are through these bug bounty brokers.