I end up spending ~$10K/yr out of pocket to speak at and help run conferences. Not for biz-dev, just for fun and to make a difference. Many, many others in the infosec community do too.
Some thoughts from 5+ years of my expensive hobby.
I usually ask events to cover travel (except small nonprofits), sometimes an honorarium from _blatantly_ commercial ones.
Tip: Ask Sales, Marketing, or Operations about taking meetings while there. Often they’re happy to have you out there on their behalf!
Tip: If they’re reaching out to you, you’re in the drivers seat.