it's very hard to make 50btc, in last year i made arround 10-20btc (from trading etc.) but i withdraw it everymonth for cost of life and i lose some at trading and i lost 5btc my wallet hacked.
it's not exactly hard, but to earn much you need to have much.
The more you have, more profit you make in each trade. You can lose more too, so at the end it depends if you are a good trader/analyst or not.
@topic
Maybe some day a can quit my job and live just from trading, but right now i dont earn that much.