You can start giving out loans and charge 10-20% interest with collateral to people, even on these forums. That's a nice way to make some profit!
That can be one way to double your bitcoins.
I prefer Gambling, Gambling and Gambling, as I want to double it in a quick way, I would prefer to take a risk and even if I loose doesn't matter as I know that the day luck favors me, I can make it double or triple in a single day.
The only way to move forward is to work hard and save. If you gamble, you're moving further backwards.
gambling give you more adrenaline and more scared with hirghrisk but you can try it if you ready to lose
hard work is how to earn more not for double it,,
all way have a risk and profit
NO PROFIT WITHOUT RISK