In my opinion, everyone should change careers at least once in their life. After 10 years of doing the same job, you feel that there is nothing new for you in the field any more, although you continue reading and attending conferences and workshops. Stagnation stops your development as a personality and as a professional.
I have changed my career from teaching English and French in Europe to web design in the U.S., and feel happy about it. I am a graduate student in web design and development, and some people think there could be no job for me after graduating. Designing web sites is a creative and artistic way of earning money. I hope employers will feel my passion for design and offer me a chance to reveal my talents. Good luck to everyone who supports my point of view and isn't afraid of changes!