The best way to multiply your coins is by trading, no doubt it also involves certain level of risk but its bit safer in compare to gambling.
Trading is not just a bit safer than gambling but it is a way more safer than gambling.
In gambling no one knows when he will lose everything but in trading it depends on you if how you do it, if you select the best coins you will earn profit and if you select the wrong coins then you will pick up a loss.
Yup and I think altcoin trading can give you some good profits in future, and 7 btc in not too small amount so if you don't want to take any risk then save it for future.