IMO, there's three driving factors behind switching careers:

1. Personal Happiness. If you hate what you do, chances are that negativity is affecting other aspects of your life.

2. Financial. We work to live, not live to work.

3. Future Job outlook. If you suddenly found yourself unemployed and looking for work, do you feel comfortable/confident enough your odds of finding another job?

If any of these apply, then strike out and make waves. If they don't, it doesn't mean that you shouldn't change careers, but I'd consider something else first - like a new hobby or improving another aspect of your life.