A good investiment in my opinion would be casino bankroll. If you invest $20.000 on it (28 BTCs), you can earn 4.48 BTC monthly income... I don't know if the casino limits a max investiment allowed. And it's not guaranteed, I'm considering you can make 16% profit monthly, but it surely can change. Tell what do you think.
I agree that one of good investment is investing in Casino Bankroll but investor should be aware that not all the investment in Casino gives a positive ROI. there is an experimental investment and at the same gathering data and displaying the profit in public on some casino bankroll and it has proven that 2 out of those 5 Casino keep on giving negative ROI . I forgot the title of the thread but it is here in Bitcointalk.Org, if I can recall it is in gambling section.