Yes, that's true, the casino won't make someone addicted to gambling but it's ones own actions that either make them addicts or not. Those who gamble a lot often end up as addicts and those who gamble in moderate way doesn't get addicted at all. That's why one should learn about gambling responsibility so he/she won't get addicted to it.
Gambling addiction can't actually be a general effect on online gamblers . Gambling either offline or online doesn't really tell if a gambler would become an addict or not. Gambling addiction gradually grows from a result of over pilled bad and unhealthy gambling habits and routines. Even before this digital age where gambling online became a thing , people used to gamble only offline before in traditional casinos and back then , there were both addicts and non addict gamblers.
Similarly today , the online gambling space to me brought more of like a flexible environment and method for gamblers to still enjoy their gambling activities anywhere and any time. Still that isn't an excuse to grow an addiction.