if you buy bitcoin now and if there are any fork is happen, then you might be get another coins for example you have 0.1 btc, after the fork you can get 0.1 btg for free (i think like this based on bcc). and yes i think if you sell your btg, you are make double money but its depend on how much the price of btg. if its equal like bcc, then you can make profit from free coins.

this is only work if you don't spend your btc in the exchanges or in other wallet because when bcc come out, whoever which have btc is also getting bcc with the same amount of the btc we have.