The marginal audience member sets your speaking baseline
Public speaking aimed at spreading ideas is a sales problem: you're targeting the marginal attendee — the one who'd leave if friction were even slightly higher.
Lose that person, you lose the follower who might return to your next event, volunteer for your organization, or amplify your message. Economics has a pattern here — the marginal buyer sets the price. The marginal listener sets whether your ideas spread.
If your talks touch existential risk or other high-stakes topics, the return on investing in engagement and retention is immediate.