Here is my methodology to double your money using BTC:
1. Invest whatever amount of fiat which you want to invest in BTC. Let's say $100 or $500.
2. Wait until the exchange rates increase by 100%.
3. Convert your coins back to fiat, at 100% profit.
Quite simple. Isn't it?
So easily you said, but this wants to work out in real life. Suppose If we buy $500 worth of bitcoins today then when it is going to double? Today price is $2600 1 BTC, so if I want to make my investment double I need to wait for until the Bitcoin price reaches $5200 is this easy? And how much time it will take? What you said it's right, but it takes a long time to make double profit.
Here's a surefire way to double your money, since these markets are some of the most highly manipulated markets one can participate in...
1) Send your bitcoin to an exchange.
2) Buy ETH with it.
3) Use that ETH to purchase some random ETH crowdsale token.
4) Sell it in the inevitable 3-4x hype bubble that is every cryptocutrency asset (we go full retard, every time. Observe BAT, SNT, REP.. back to NEOBEE, ASICMINER, SATOSHIDICE)
5) Convert back to bitcoin, and you're all done
That was easy
Or you can pass go and just send it all to me. I have property in sunny Nicaragua that's a bargain, I promise. Easy 100x returns, guaranteed.