As someone with more than 15 years of experience and who has leveraged my open source work to improve my own career, my two cents is that GP has a fairly sober view on OSS as a job: Filippo is an outlier among outliers. Most people simply don't have the opportunity to build a reputation from multi-year, full time, corporate sponsored open source work on a high visibility project to leverage when leaving a cushy job to pursue higher rungs in Maslow's pyramid.
Yes. This is a variant of building an OSS project using company funds then leaving the company to commercialize it. It's a real path, but requires taking advantage of years of corporate largess. Not impossible, but some big "if"s involved.
"Possible" is very different than "likely".