Is he really strong counter example? If you actually count bounties he got this year so far, it's less than $50,000. I think he could easily earn more working as some kind of security engineer (with way less flexibility though).
Author of the blog post here. I want to make it clear that I had multiple full-time jobs along the way that paid over 200k AUD/year and it required a lot of effort to do both bug hunting and work full time. I only did bug bounty hunting full time for around a year while I was traveling around Europe. I just really love hacking. Bug bounties landed me my first job in the industry and have led to countless opportunities in my career so far.