Ehhhhhhh...I disagree.
1. Most of my clients tend closer to seed stage than to well-funded.
2. You don’t need security expertise or money to run a good bug bounty program. You can start one immediately. There are enough high quality resources available for free on the internet (that are not content marketing) that you can learn most of the important unknown unknowns.
For example, I think this is excellent reading for any young company thinking about security: https://medium.com/starting-up-security/starting-up-security...