bhutocracy

That or your homeloan are the safest bet. Basically any non deductible debt is your first port of call from highest interest to lowest. Of course in a lot of countries homeloan interest is quite low atm but it's the easiest money you'll "make".

That said it all really depends on age, earning capacity, income insurance and the risk of the investment. If someone is young, can generally make good money and can deal with the worst case scenario then it's not the worst idea to gear investments as there are still enough working years to make up for any early investment mistakes and you can pull yourself out of the hole. If you're a bit older, don't have the best earning history and a failure would hollow you out then you should invest accordingly ie more conservatively.
Forex trading, CFDs, margin loans etc are all things people do without blinking and are about as risky as a low interest loan for bitcoins. However I do have to say bitcoins are the most volatile currency so it's like forex on steroids and probably without any of the available tools to minimise risk (stoplosses, guaranteed stops etc). It's also far more opaque. At least with the USD you can make some kind of well founded prediction (like the movement next Feb when the debt ceiling dance happens again) and it generally should obey previously observed phenomena in relation to public information.

It's all about what you invest in an why you bought at what price. Speculation isn't the sort of thing you can do without research and actually knowing a lot about the market you're investing in.. Personally a low interest loan would probably be used to expand core business.

Doing the sums now.. your loan is for ~3k given BC moved several dollars in your stated time frame if the board times match up.. So we're not talking business start up money (unless it's a small import from China sell locally via web online biz).. Its pay off the credit cards or put it all on black money.