Should be strictly avoided, the casino type of investment will not guarantee full profits. Better to play right away than invest in a casino, I've tried that in the past, investing in a casino doesn't give me any profit, for example today I get 1% profit tomorrow I lose 1%. It just spins in place, at worst ever my money no left at all.
It depends on our own preferences, some people prefer to invest in the bankroll than gambling against the house and vice versa.
Investing in the bankroll should be taken as long term investment, you cant judge it by just 1 day or week result of your investment.
What you need to understand is that there is always a risk and you should aware about it and ready to take the risk no matter you are investors or you choose to be gambler.
What happens is that many people do not really know much about how a casino operates, casinos earn money even when there is a few gamblers that get lucky and earn a lot of money.
And they can do this because they take a long term approach when it comes to their gambling operations, they know that with the house edge being on their favor sooner or later they will make money, they just need to have deep enough pockets to sustain a few big losses in the case a few whales happen to win big, this means that your investment in a casino can be down for months but over the long term you should make some money with it if the casino is being managed correctly.