If you are privileged then your environment is your support group. It validates you consistently and effectively. You don’t need to seek out a specific support group. You already have a support group called “my environment/the world I live in”.
If you are not privileged your environment probably invalidates you consistently and effectively.
Another way of saying this is: it violates your boundaries consistently and effectively.
Another way of saying this is: your environment subjects you to physical, mental or emotional abuse consistently and effectively.
If you struggle with addictions or illness I believe that might actually be a consequence of abuse rather than being something inherently wrong with you that isn’t wrong with non-invalidated people.
For what it’s worth, if you’re being consistently invalidated/abused/ill/struggling with an addiction then it seems likely that you could benefit from more validation in your life. Validation can come from (safe) family members or friends. It doesn’t have to come from a formally structured support group or a counselor.
In any case I don’t agree that the primary reason people need specific support groups is because there is something wrong with them.
I think the primary reason they need them is that something is wrong with their world. Or was wrong with their world, and they are still dealing with the fallout of that.