Longevity with fair to bad reputations. What a gambler should look for in a casino is reputation. What people should be expecting from the casino now is accounts restricted from withdrawing. It is possible that the casino misappropriated their customers money and not having enough money as before.
The thing is that many gamblers just invest in random sites without checking their reputation in advance thanks to getting tempted by their promotions, high value odds etc and end up regretting later on.
Greed is the problem here. Smart gamblers do their research properly before choosing a casino to invest in as you mentioned yourself.
OP's concern is not about investment, it's about being a gambler and then getting limited when you're winning. I would understand limiting the bets but not limiting the withdrawals, as that is your money, and you should be able to withdraw it anytime. As mentioned before, it's a bad sign for a casino and it demonstrates that they might be facing liquidity problems, which is a fair warning of possible bankruptcy.
Investing in a casino may not be a thing nowadays since reputable and popular casinos already have their own funders. Unlike before, when they could run an ICO to easily lure investors, most of them failed because they didn't have a good long-term working plan.