They say investing to gambling sites is much safer than doing trading. But if you really want to have control on what you will earn at the end of the day better do trading than investing to casinos.
"Trading" is a zero-sum game (atually worse because of fees), so it's very unlikely you have a system that makes you more than about the 50% annual returns that I estimate investing in Just Dice gives you.
Casino returns are quite stable and predictable. Especially in the case of Just Dice, because most of the profits (nearly 90%) come from staking, and the amount of staked coins is about the same every day (
https://just-dice.com/misc/wagered.txt).
I think if you invest in some good coins then you may easily make that 50% profit from these altcoin investments in a year. Look at people whoever bought most of the top altcoins today one year ago then they all made more than 50% but can't tell you how it will be in next year.
Casino bankroll investments are good in the long term but there is no guaranty that you will make 50% profit in a year time. I suggest you can do both some invest in casino bankroll and some invest in good altcoins and bitcoins.