I've always shared with students and friends that trading for a living is not as easy or simple as it sounds. that's because there are several keys that go into the equation to ensure you are successful and stay that way (with regards to trading for a living).
One most important key is that you must be properly capitalized and if I were to poke at a general figure (i know the figure is specific to different traders), i would say to have at least $50k for trading.
2nd and last key i want to mention here (there are many others) is that you must be prepared for drawdown periods.
Cheers!