If you can invest big amount to buy some btc then i guess you can earn huge profiit in near future! because btc price is upper!
Gambling is one of thr thing i know that you can able to get 1 bitcoin or much higher income in a month. But it is too much risky than trading, gambling is for people who have lot of capital but if your capital is few i thing you must go on trading without requiring minimum investment.
yes gambling is really the shortest way of earning bitcoin and you can make more than on bitcoin in a moth, but in fact gambling is one of the most risky way of making money, there are more chances to lose your own money,
Never forget that gambling is the fastest way to loose money too and most of the times you will loose your money in it as you cannot be lucky each and every time so its better to find safe and concrete methods of earning bitcoins which can give regular income and that is possible with trading and by joining good signature campaign and if you have good knowledge of trading then you can make good profits from it regularly.