Yes, you CAN trade for a living. But you need to know what to expect. Unrealistic expectations can frustrate your efforts and adversely impact results. Here's what NOT to expect:
1) Do not expect trading to pay your bills.
This is not just dangerous, it is downright suicidal. You are likely to take above average risks if you are under pressure to produce enough by a certain date. If the trade goes against you, you will take even more risk to recover the loss and still make the quota for the month - a process that can easily degenerate into a death spiral. You should have at least 3-6 months of living expenses stashed away in cash/CDs to take the pressure off trading, or find a way to trade part-time while you are going through a learning curve. Some stocks are difficult to own unless you can watch them throughout the day, others are best left alone to do what they set out to do.
2) Do not expect a regular paycheck.
Many traders expect successful trading to generate regular monthly income. This expectation is reinforced and magnified by TV infomercials where dumb looking people "making $1,000 per day by 9 am" day in and day out make you think: "If THEY can do it, I sure can."
The market is not linear. It typically presents 3-5 great buying opportunities a year, when multiple stocks break out. Fast runners also tend to top out around the same time, when market conditions deteriorate. Your annual income is therefore more likely to come from 3-5 lump sums per year interspersed with many small losses in between.
3) Do not expect to beat the professionals at their own game.
Any stock you touch is likely to be traded by a handful of professionals who know more than you do, have more capital than you do, and have been doing it longer than you. Do not expect to outsmart them. Instead, find a method that will give you an edge. There is more than one way to trade.
4) Do not expect complete clarity.
As a matter of fact, expect the unexpected. No amount of due diligence will protect you against sudden losses and setbacks. No system works 100% of the time. Expect things to go wrong and be prepared to deal with it. Trading is not an exact science. Expect to operate on incomplete information and contradicting signals.
And finally:
5) Do not expect to make a killing.
The amount of money you can take out of the market depends on the amount of time and effort you are willing to put into this business. There are no short cuts. Instead of focusing on "how much you should expect to make," focus on how good you can get. If you follow a good system and are disciplined, profits will follow, almost as an afterthought.