Most open source projects will have a donation page / link, so it relies on people feeling compelled to donate because the software provided is useful to them.

Lemmy for example has options for financially supporting its development. Some Lemmy instances also feature a link to a donation page to cover the hosting costs.

Some have an organisation behind it, like ~~Firefox has the Mozilla Foundation to finance it~~. Actually it's the other way around, see ahal's comment below

The team behind VLC has a "for profit" branch that adapts the video software for companies, allowing them to also finance VLC's development in addition to donations.

Like others have mentioned, there are various options (donations/sponsorships/grants) that larger projects will generally have some of, but for smaller projects (99% of what's out there, by project count if not usage), the answer is simply "it isn't." It's done as a hobby, as a resume booster, or with the hope of eventually becoming big enough to hit one of those revenue streams.

I contribute and run some open source projects. Some projects receive sponsorships and contributions, some are backed by companies, a lot are just someone doing it on their own time, very few can actually meaningfully support the people working on them. Personally, I receive no money for mine.

depends on the project. Some projects are spun out from major corporations. Others are one dude making a thing and it gets used everywhere and taken over by venture capital firms.

Some projects will have sponsorship, there are also government grants they can get, but I would say most comes from regular users doing reoccurring dontations.

Core developer of an open source software suite here. We make money by doing the following things:

• We offer a free and open source community package that has the basics. However, we offer a number of professional packages that we offer yearly subscriptions for.
• We host our software. We charge by the number of active users.
• Custom development.
• Paid support like migrations or troubleshooting. Also helping external developers develop custom modules.

This allows us enough income to develop the community part of the software.

FOSS is free, OSS doesn't have to be. Very often open source software, of which the commercial fork is being maintained by a company, that company will profit from businesses using the software. Idk about VLC but Moodle, for instance, is open source and updates for it are based on a subscription model.

The license agreement for OSS will often state that you are free to use it in your own home, but if you start commercially using the software, they expect you to pay. Some open source projects can get resold by service providers this way to handle deployment of updates, provide support, et cetera.

I’d assume it’s mostly donations

Our small company paid a prominent (of that specific driver) open source driver writer for prioritisation of some work more than once. All the code was GPL.

I know it's only one data point but it's one way.

I think usually it's just about costing the competitors money to try and fuck them. That's the payment. 3ds max is priced unfairly and it's unreasonable, that's why Blender exists. Autodesk bought eagle cad, made it cost money, that's why KiCad got made. I take pride in supporting open source everything in protest of how enshittified the world has become. It harms those corporations when more people use open source which is a cause I can get behind.

Ways open source projects get paid for:

• people do it as a hobby and don’t get paid
• people rely on donations
• government funded software projects are usually open source
• software created in an academic setting is usually released as open source (this often overlaps with government funding, but not always). Many important open source projects started in academia. Many open source licenses were initially written by academia for those projects (BSD was created by UC Berkeley, and the MIT license was created by MIT).
• Sometimes companies have a business model that doesn’t involve selling software, and they don’t really benefit from having that software be proprietary. They may open source their software because it gets other people to use it, and by extension gets people to buy their paid products. For example, there are some free, open source software projects by Nvidia, but you would need to buy one of their graphics cards to take advantage of it.
• Dual licensing. One strategy is to release your code as open source but under a copyleft license so it isn’t business-friendly. When a business wants to use it, they pay for a proprietary-licensed copy instead of using the open source copyleft version.

Lots of OSS is created by people who want to create something, and happily gives it away to others too.

The problem is when others start depending, and demanding, work from that person. There is no good solution to that problem at the moment.

My company hired at least one open source guy. The original code is internal to our company and he’s allowed work time to maintain it

Loads of donations for one. You ought to donate to some of your favourites too!

Either by salary by hiring an engineer for a company, by issuance of grant, or by issuance of funds from donations via 1099 or similar.

If your only aspiration for creation and improving the world is making money, you are a waste of a human.