i think it totally depend on your interest that where is your interest, if you are interested in gambling then you can invest int in gambling but gambling also need some experience and skill.
Of course, if you are interested on one investment, it's either you have idea about it or you will find one to make it more interesting. 12 BTC to be used in investment is big enough, you could do day trading with that and earn, aside from that you may try risking on investments or investing in gambling sites. its all up to you and where your focus is and what you think is easier for you to manage.
12 btc is a large money and you are right recommending trading or gambling and that depends on where the author feels comfortable and where she thinks she is earning. Earning bitcoin is a hard one, its much better to do a signature campaign than to invest. But if the author will ask me I will recommend trading and Im sure she will earn big using that huge amount.