Volunteering for the sake of gaining experience from it, or of adding one more item to your already long list of activities is better than not volunteering at all. However, gaining experience from it should not be the primary objective, nor should be bragging rights. The primary reason should be that you want to volunteer your time and talent to help a worthy cause. You do not only want to gain experience from it, but also you want to help, you want to experience it, you want to feel the humility, and you want to help more (or not anymore).
I dislike the term “check your privileges”, it implies that I know something, and I know what privileges are. In reality, I do not know. However, in the case of volunteering, I can safely say "check your privileges” before bragging about it.