Hello my friend. I know that in California, gambling is mostly legal from the age of 18, but I'm not sure. You can find out about how old to gamble in california yourself on this site https://ponbee.com/gamble-in-california/ It says in detail which gambling games in California can be played from the age of 18, and which not. So I am sure that you will learn a lot of new information for yourself and can start gambling.