This is all true, but it’s interesting how people often forget another simple option: the software is commercial - it is simply sold on some website/store. Just like you can buy the game Mindustry on Steam, but it is Libre Software and even though you can get the build for free on GitHub and its itch.io page, people still pay for the Steam version. I wonder why people forget about this option, since it’s probably the simplest one.
Of course, Steam is a proprietary, unethical platform, so I’m just using it as an example - I’m not saying we should sell there.
Based on what you said, I’m not sure what you mean by “open source”, but Free Software gives you the right to distribute the program (https://www.gnu.org/philosophy/free-sw.en.html#four-freedoms). So anyone who owns a copy can legally share it with you. There are commercial Free Software projects. The game Mindustry is one example.