More of "in what kind of situations is it practical?".
In general, it feels like something absolutely unstable, and/or a trickle.
The stability depends a lot on the supporter base, and how well you achieve to bond with them. It also depends on what country they're living in.
Switzerland is a rather good place for a supporter base. People usually have some money to spare, and are often very willing to support a "good cause" with it because they feel that their lives are too busy to do some stuff by themselves, although they might like to. Note, by far not every Swiss is like that, but people like that seem to be more common than in other countries, I guess mostly because Switzerland is filthy rich overall.
So there's one factor of stability. Another factor is the currency the donations are made in. I have seen a significant payraise over the last 5 years, not because people donated more (we weren't trying to expand our base, since we had enough, and too much money can be a pain in the ass when working with donations), but simply because the Swiss Frank held stable while the euro was steadily dropping.
But in the end, the most important thing is how much people believe in you and in what you do. As long as you can keep their trust, you keep their funding, if their own economy doesn't screw them over.
In the whole, I expierienced it as a very stable thing, more stable than the salaries of some of my friends. But we had a very small supporter base with a very close connection (some 130 people overall, not all of which were donating, but all of which who we could rely on to chip in if things went south for some reason.
The dynamics are a bit similar to a fan base, I guess, and that brings with it some very unique dangers for your personality, and you might feel a bit more responsibility than if you're just spending "the organisation's money", but if you manage to form a personal bond between yourself and the donors and they trust you, it can be a very stable arrangement.
OF itself is one such case - it only needs $60 or so a month, and quite often it takes weeks for the donations to reach the mark, judging by the donation bar.
Actually, from what I see, OF has together at least 70% of the neccessary funds during the first week of the month, a good deal of that being money left over from the previous month. Since most people will donate at the end of the month, when they get their salaries, OF seems very stable, and there has once been discussion what to do with excess donations... As I mentioned, that can at times be almost as much of an annoyance like having too little.
Closest think that works of which i'm aware is video bloggers, LPers and similar video/podcast content creators.
It's a bit similar, but can be quite different in execution. In this case, you are not relying on your base for the money directly. All you have to worry about is to keep them happy enough to keep watching, and someone else will pay you. The dynamics if people are paying you directly are a bit different, but it can work in this context too. The most famous example I can think of is dwarf fortress.
paid subscription (Patreon)
Patreon is not paid subscription. Paid subscription is paying to get access to features that are otherwise unaccessible. Support via Patreon is more like paying so everybody can have access to something, because you enjoy it so much or because you think it's important. It's basically the same I did for the last 10 years, except what I did was not directly related to art.
I grew up with the notion of the Internet being a data storage system.
So, it's only natural to go through the details of whatever interesting thing you found.
First, people have very varying degrees of "being interested", and I don't mean that they're just interested in different things. People have a limited ammount of interest to spend, and that ammount is not the same for every one. That's basically what the term "attention span" means.
Second, I got to know the internet (only had internet since I was like 17, so growing up isn't the right term) primarily as a communications platform. But the truth is, that the internet is whole lot of things. It is without a doubt the vastest data storage ever created, it is also the most used communications platform, it is the worlds largest distribution platform for
everything, and by now about the most used entertainment platform too. People do not always browse it with the same mindset. And usually, when they are looking at pages your employer doesn't pay you to look at, they are either communicating or looking for entertainment.
For people like you and me, learning new cool stuff about things that interest us
is entertainment. For a large junk of the population, however, this does not apply, or only in special circumstances (I have taken a lot more to brainless, superficial browsing since I have kids, for example, because a) I'm often too tired to concentrate, or B) I'm not able to concentrate because somebody's screaming my ears off...).
Hm, have you tried being cynical about cynicism itself?
Unless it helps fix something or use something, it's pointless.
I'm afraid I'm rather good at "pointless" when it comes to general pesimism and outlook on life...