That depends. If you're just the type of guy who, according to your friends, takes great pictures, you should very, very seriously reconsider. Even if you have a good, proper education as a photographer (e. g. via art school or apprenticeships or both), only very few will actually make a living off it. Kind of like musicians. But as others have pointed out, there is a rather big supply of `photographers' these days. Traditional venues of photographers are now taken over by non-professionals or semi-professionals (e. g. wedding photography).
My cousin is a pro photographer and now he makes a living off it (well, I suppose he makes most his money as a director now, but photography is what got him into the business). He started out as a sports photographer. The reason he could start is because my uncle bought him his equipment (the first `affordable' dslr, a Canon D30 plus some ray gun lenses). But even then, he drove 85-120,000 km/year, slept very little, immediately rushed to his laptop and used a very slow modem to transmit his images. If he's second and doesn't sell a photo, too bad!
He also photographed real estate for my uncle and used his contacts to make a network. After a while he started shooting bands (cd covers/album art, promo shots for magazines) and did a few modelling jobs in a studio. He then started and finished an apprenticeship as a media designer (a lot of work and almost no money). Somehow he met a friend who wanted to make a documentary and he wanted him to do the stills. So he worked for a few productions and at one point ended up working for a big German car manufacturer as a director for ads and commercials. He still works as a photographer, but that's probably just the icing on the cake.
This is a very condensed story, it took him 12 years or so to get where he is. As you can imagine, he had to upgrade his equipment along the way -- very expensive. He had to work very hard, but he was also lucky in that he had support (I don't want to take away any of his achievements, but it would have been much harder without his father's support in the beginning). It's very helpful if you're a people person, because you live off networks. The `I know someone who knows someone who knows someone who could do that job' is your life source.
One obvious thing is that in most cases, you will not make art. You will make pictures of condos, perhaps vases, sports stars on the field and most people (read: clients) don't like artsy stuff and experiments. Think of shovelling snow: somebody's got to do it. It's very hard, because there is an abundance of genuinely good people. You have to love what you're doing.
If you're interested, I'd recommend you start an apprenticeship somewhere and help a photographer.
