Companies have shareholders and responsibilities.

They have to choose between contributing a salary for a year to open source projects that are the foundation of their business or fuelling one of the corporate jets for an hour. Making these sorts of tough decisions are what the 10mil+ in bonuses are for at the end of the year.

I suspect many of these open source developers are employed in this capacity on some level by for-profit corporations (which sadly does bring a high degree of dysfunction in terms of resource allocation). But I can't imagine being this productive as a side-gig.

well, most successful oss projects are paid for through that one guy at the corner cubicle that has very few company responsibilities, but he maintains lib-fart-chart, which is also used at said company.

A lot of oss contributors work for big companies