If someone wins big, then your returns will go down in a big way. Both can happen in casino bankroll investments. So it is good if you can diversify your money and put in few good casino instead of just in one or two. You can make a good profit if you invest for longer term but in short term can't give any guaranty.
Yeah . If you are to invest in a bitcoin gambling casino site. You should have another source of income because this takes time before you earn profit. There are times that your investment becomes negative because the casino is loosing at that time. But, if you make it as long term investment. It will surely guarantee profit since I don't see any casino site being lost. Also, selecting the best casino site will lessen the risk of scam since you are in a long term investment.
Yeah investing to different casino's and depositing there as many as you can will always give you the favor. And when you have some loss with the other site then you can just recover it from the other casino's that you invested. With those scam casino's, it's better to identify them nowadays with the help of scam busters.