Playing/gambling at online casinos don't have many risk anymore. You have tonnes of regulated casinos out there so you can try one you are attracted to. Legit online casinos make profit through typical methods, always having advantage of being "house". House will always win some. So you don't need to worry if you win - they made enough profits that can cover your win from them. I think if you are seeking good legit online casino, enough is for to look at legal bindings and withdrawal (money) speeds.
With numerous legit online casinos these days, you will never be prone to scams as long as you also gamble responsibly. And never worry if you made a huge win, with all the profits that they made out from those players losses, they will always have sufficient amount to pay for us, except for casinos that have not build its name and reputation in the gambling industry, they might struggle at first especially for jackpot wins. But rest assured, before they start their business, they have anticipated it already on paying their lucky players without payout delays.