Patrick’s heresy is not an unreasonable statement. My current employer grew to a $34 billion market value using, creating, and supporting open source software. But there are plenty of stories of open source developers working on key projects that are barely able to sustain themselves.
Benefits of use
It’s clear that independent software developers benefit from using open source software. If nothing else, the programming languages themselves are immensely beneficial. Much of the tooling, frameworks, and libraries used for developing applications these days are available for free under open source licenses. The economic barrier to entry would be much higher if everything had to be paid for.
Benefits of development
This is where the answer becomes more qualified. Contributing to open source projects can open the door to being hired at one of the businesses that make good money. But that’s not attractive to everyone. And an “everything should be free” mindset can make it hard to earn money.
It comes down to what you want to get out of it. If you’re doing it to make money, then it might not be beneficial, unless it’s a boost to your resume. But for some people, contributing to open source projects is a hobby they enjoy. I got started out of a sense of giving back to the community that provided me with a free operating system. The fact that it eventually became a paying job is a nice benefit.
Harm of not contributing
The flip side of the question is “does not contributing to open source harm indie developers?” The answer is “yes” far too often. A lot of development positions explicitly or implicitly expect your GitHub profile to be a key part of your resume. But not everyone has the privilege to be able to contribute to open source projects in their spare time. Hopefully that understanding spreads more broadly through the industry.