PetaPixel has a great story by 30-year-old Brendan van Son about how he has been supporting himself for the last 5 years as a travel photographer/journalist. During that time he has visited almost 80 countries. He provides a lot of very valuable detail for anyone thinking about travel photography as a career.
In general Brendan’s answer is not just taking pictures, but to have multiple sources of income. His sources include: (1) Magazine and Newspaper work (probably the smallest source), (2) Stock, (3) Client/Direct Sales, (4) Leveraging Social Media Followings, (5) Blogging, (6) YouTube, (7) Teaching, (8) Freelance Travel Writing and (9) Tradeouts for Hotel Rooms and Tours.
Check out the story
here.