with a capital of 17 bitcoin? you want to get 7 bitcoin. it may even be more than that, but you have to have a commitment, my advice BTC that you use for the new coin trading, because of the new coin trading percentage we get to be 2-7x from the initial price. Do not ever be tempted kind of gambling! 
you read the post carefully as he do not have 17 BTC but have only 7 BTC and he want to earn more bitcoins with that so that he will make 17 BTCs with that 7 BTCs. and for that only trade is possible or any other smaller business.