I want to see realistic answers and I don't want to hear that it is NOT possible.

So you do not want to hear the general truth. Because that it is for the most cases. Unless you are lucky. It is possible to grow it some percent, but not doubling it. At least least you need to be lucky to do that. For example with Bitcoin (BTC) or with other high volatility asset. Let's say that Bitcoin (BTC) is $2000 USD, you buy 0.50 Bitcoin (BTC), and then 4 weeks later the Bitcoin (BTC) goes up to more than $4000 USD, and you sell it. Yes, I know that nowadays the Bitcoin (BTC) is worth around $10 400 USD.