To make a living, you mean replace salary. It requires capital, imho 250k minimal. Trade conservatively to preserve capital to return 25% +-, using option premium, cap gains and dividends.
I've posted on this subject before but here are some more realistic numbers:
Assume you can make a Sharpe Ratio of 0.5. Maybe you'll do better - bravo. Maybe you'll do worse (most retail traders lose money, so 0.5 would be much better than average).
That implies a full Kelly risk of 50%, and half kelly of 25%. I'd use half Kelly maximum. That equates to an expected return of 12.5% a year with 95% of your annual returns falling in a range of -38% to 63%. Your probability of losing money in a given year is around 30%. Your probability of making less than 12.5% in a given year is 50% (assuming symmetric returns).
You clearly can't expect to make money every year so you need to either have (a) several years of living costs saved up to cover the times when you will don't make enough money or (b) passive income from dividends / bond coupons or (c) a combination of both (or (d) another job or income from a spouse but we're talking about 'making a living from trading' so let's assume that's what you're doing).
Let's focus on (a): Mathematically over 5 years you have roughly a 3% chance of not making 12.% in any of those years so I'd personally want to save 5 years of living costs in cash.
Let's say that you want to replace $50K in income (I'm ignoring taxes). You're probably going to want to have 5 years of living costs, minimum, which is $250K. At 12.5% to generate $50K you need $400K. That's a total of $650K.
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