I think you suggest are risky and i think theres no safe place to invest bitcoin.. its better to buy and sell stuff.. like buy high rank account for low price and sell it for high price.. or some serial keys and sell it high.. this is better and i thin you are far in risk.. also investing at casino is so risky you can be lose or they will run your balance..
All investment are risky including buy and sell high rank bitcointalk accounts. Regarding invest on casino, yes it is risky as well but you do not need to worry that they will run away with your balance as long as you invest in a trusted casino.
I find it also risky, if you are going to invest in casino and you are hoping to earn there with interest, no way.
Since it is also a gambling site, we all know that gambling sites are not stable that way unless the site is programmed that higher chance of winning to its gamers.