How much would someone with a sound strategy need in order to generate consistent income?

I ask this question assuming the person trading has a sound strategy in mind that works and is rather seasoned as opposed to entering the market with a lump some of money hoping the best. Say for example a short term swing trader, how much would that person need to make in order to generate a steady income of 1-2k a month? how about 3-5k a month? Obviously, the market is volatile and some months are easier than others. But generally speaking if someone were to learn a trading strategy, practiced paper trading. how much REAL money would they need in order to make good passive income?