solicits companies to sponsor specific feature requests that they feel they could make significant use of.
Bug Bounties work similarly. People add a tiny amount they are willing to pay for a bug fix, eventually someone gets motivated enough to fix it.
But mostly, open source projects usually don't make money and are only supported by volunteers.
That means in a weird twist, many of the core systems of the Internet have historically had a lack of funding, yet they empower the entire Internet to run smoothly.
The NTP (Network Time Protocol) global time servers, for one, haven't had much money for years. Some people volunteer to have their computers run as time server relays, others volunteer some services here and there, but overall they operate on a volunteer basis. Companies like Apple and Google submit 'urgent' changes they want submitted or corrected to to the time servers, but never throw even a $5 donation their way. They got a brief infusion of cash after making the news, but that's about it.
OpenSSL had been running on a tiny budget until the Heartbleed bug hit. Then corporations who were making millions and sometimes billions by leveraging the product were guilt-tripped and pressured to throw some money at them.
Fortunately after these hit the news, a few groups started taking some action to get grant money and perhaps more regular funding to "critical" projects that have no money.
But for all the rest of the products, especially free games, the mantra is simple: If you are not paying for it, you are the product.
Advertisers pay a fraction of a cent every time they get your eyeballs, and they pay another tiny amount when you click a link or buy a product through a tracked ad. Somebody has to pay for bandwidth, somebody has to pay for servers and electricity.
For products I've worked on you can either pay indirectly by being exposed to ads and getting some of your information detected and sold indirectly through the ad network, or you can pay a small cost to get completely removed from the ads, meaning they also stop siphoning your data away through that product. Either you pay, or you become the product.