Interesting answers. I suppose that I am a little different from the norm in this respect. By all practical measures I am now a professional photographer, though I still take a very amateur view of the world - if I don't think I'll enjoy it, then I won't do it.
I started photography in the year 2000 and I possibly did have a bit of Gas at times, but as I started with a 1MP digital camera, better cameras actually did improve my photography.
For about 14 years I was strictly amateur and I collected lots of photos, mostly travel, printing some for filing in A4 folders or as a yearly calendar and posting many on the internet. I have always liked to share my photos, and I used a variety of sites to do this, including a very good critique site, long gone now and some posting sites, of varying quality. I remember one where you posted a photo and others would score you points for quality. It started of ok until some of the posters discovered that you could get more points by posting lots of points for other users. This quickly snowballed and it caused a lot of contention among users, to the extent that the site eventually closed, and reformed with a new name - Photopoints! I never joined that site, but as it quickly vanished, I assumed that it disappeared up its own a******e. Still, that type of thing has proliferated.
Another site I joined, was called webshots. I think it is still around, but it was bought by someone and they wanted to charge for use, so I left. I apparently had 7,000,000 views on that site, which has always astounded me as it attracted almost no paying customers, not that I really wanted them. I also used a site called 1x.com (still going I think), which did have some genuinely good photographers of the Northern European arty variety. I got angry with their attitudes to photography and left, but it was a good learning experience.
About this time I decided to retire from my job in the Computer Industry and move to the bush (Australian for country). Several of my friends suggested I take up pro photography and I did think about it, but came to the conclusion that: a) photography didn't pay very well, and b) I'd most likely have to take photos of things I didn't like (eg weddings).
So, I started my own photo site using Smugmug and concentrated on taking the photos that I liked with no thought for any professionalism. I did quite a bit of travel, climbed volcanoes and wandered around rainforests, and I posted those photos on Smugmug and Flickr. I started to become obsessed with fungi photography, which I thought had zero chance of either selling or being widely popular. I had discovered when entering comps with fungi photos that it usually took 3 or 4 attempts before the judges of that comp would start to see some merit in a fungi photo. I would usually win something in the end, but it was a frustrating process, so I stopped doing it and also stopped trying to get people to like them. But, I kept posting them on Smugmug and Flickr and sharing them with the mycologists I had come to know. I was happy as I was getting good feedback from the mycologists, who were in turn feeding me with good information on fungi and now my photos were turning up in Wikipedia and in all sorts of collections on instagram, pinterest etc. I had settled into a bush lifestyle and the photos were my way of communicating what I discovered.
Then I was "discovered", firstly by Thisiscolossal, an American blog which I had never heard of, but who, it turns out, are highly respected in the publishing world. Their blog on my fungi photographs generated articles in many of the major nature magazines in the world.
Secondly by the BBC and Planet Earth II. The BBC work was time lapse, but that is just a series of still photos welded into a video. It is quite special hearing David Attenborough doing the voice over for your footage - and it is very good publicity.
And thirdly by some international mycologists and NGOs who wanted me to photograph fungi in their locations to help with documented fungi around the world. This has led to trips each year for the last 5 years, Apparently having good photographs is a key to good fungi documentation and is crucial in spreading the word to a wider audience. It is also the thing that gives me the most satisfaction. It is break even as far as money goes, but it gives me the chance to visit places with guides that few or no tourists ever go to. Most places people go to are bursting with tourists. We just spent a month in India without seeing a single western person and the same usually happens in China.
All this has meant that I do very little these days to post my photos on the web, but they still go on Smugmug and others post them from there. I do the occasional presentation and there is talk of some gallery shows or science exhibitions, but that will be next year. Film work is probably my biggest advertiser now as they do use my stills for film promotion.
Anyway, that's what I do with my photos. It has changed a lot over the last 18 years, as have the opportunities. One thing that has become apparent to me is that video is now much more usable (mainly on phones). Getting moving pictures right has far more to do with the art than with the science so it can be more than a bit challenging for us technical types. Still, it is worth investigation and it will be hard to survive as a pro with just stills in the future. Not that that matters if you are strictly amateur.