Is there any websites like bc.game but allow people under the age of 18?
Why do you hurry to join a gambling game, kid? If you are still under 18 ages, I think the best option is to wait for it. AFAIK, most gambling sites require a minimum age of 18 years. I think it is a good decision, at least to avoid a very early addiction to gambling and to make sure that the user has good control of his emotional/mental. Even if no guarantee about it, but it is the best way to ensure all the users on the sites to play the gambling games properly.
I think it has to do precisely with age, underage people also like the idea of trying to drink alcohol but as many of us know it is not a big deal and yet those that are young want to experiment it precisely because it is forbidden to them, gambling is the same, gambling can be fun but it is not as if your life is going to change if you never gamble but since those that are underage are not supposed to do it then they want to do it.
But as you say there should not be any hurry, gambling has become common place and in many countries gambling is completely legal so it is better to wait until you have the appropriate age otherwise it could have negative repercussions on the development of young people as they are not mature enough to take full responsibility for their actions.