Every dev here loves throwing unglamorous volunteer work to non-developers, acting as if it's a favor.
- Most of my career was made by being the author of one popular open source platform which happened to do well.
- I've recruited people based on open-source contributions. If I want an expert in [X], finding someone who contributed to [X] is a good bet.
- The flip side is I've made (minor, helpful) contributions to many projects in part for exposure. My name is in the commit list of many systems in domains where I have wanted to work.
- Many mid-sized contributions look good on a resume, especially for a junior developer. Indeed, I've made one case to promote someone based, in part, on contributing to a library we were using (even if only tangentially).
If you want a job in e.g. network security, find something in a firewall, anonymzing proxy, packet sniffer, or whatnot, and make a PR. It's often quick, easy, and helpful. A corollary is you do actually learn a lot about a system by contributing.
I have no axe to grind here, but I think the cynicism is unwarranted.
That's more a salesperson mantra than SWE, where for every 10-100 people you ask, someone buys something. However, I've raised money many times simply by shamelessly asking.
Second good life lesson: Don't assume things about others.
People who make $1/day, $10/day, $100/day, $1000/day, $10,000/day, etc. have fundamentally different priorities and motivations. Ditto on many other axes. Good synergies are leveraged working across such differences.
Devs are expected to contribute to FOSS, write free educational blog posts about technology, and fix your friends computer!
Ask a doctor why something hurts and they tell you to come into their office and insurance will bill you.
I do open-source and write blog posts to satisfy my own desire to publicize my work, and for exposure, and to put my skills on display. Not as a race to the bottom. I could have had a career without those things.