Man people falsely believe Open-Source to be free. It's free as in freedom of speech not free beer. Technically your not paying for the software i.e. OS or application/program. But it's not really technically free.
In reality Open-Source companies, individuals, groups, and organizations make billions yearly from supporting the software. Red Hat Linux alone hits nearly 2 billion yearly in profits.
There's this strong belief that Linux for example doesn't make money cause it doesn't charge the operating system. Believe me when I say Linux is extremely lucrative in the server and support market.
Sheer fact is only when things get to FOSS, Libre, Copyleft, and Patentleft. Sometimes people just release pure free software with their own license agreement. They might state free forever with recognition of use. So if you use it and name the manufacturer person it's okay. Sometimes not even in some cases even fully free 100% without anything is left like that.
Funny but some companies make a lot of money servicing open-source community. It works literally like no joke it's one of the reasons why programmers, coders, and software engineers who work in open-source make many tens of not over hundred thousand a year. Especially if they know the UNIX style like the back of their hand. Lots of job opportunities and again not only do they make a killing but the company also makes a killing.
In the end I agree with the others O-S is very WW2 regime like a principle of having proper software verified and vetted for appropriate use. Only recently these past about 10 years has open-source had issues with proprietary and others butting in to monetize or simply be around it to make a profit.