And what do they even do
It honestly depends on you, your parents, and the college counselor offered at your high school.
In high school, my family got me a private counselor because my high school counselor was overwhelmed (big public HS), my mother’s english is poor, and my stepfather couldn’t be bothered.
Some people are great at doing college research on their own, so they use a counselor more for essay editing/proofreading than anything.
Like the above–it depends! I had a private counselor per-se; I was a part of an organization designed to help kids reach college, and thus they had two counselors that helped out students like me! The additional counselor really helped me out and made me feel a lot more at ease, as my school counselor, while she is wonderful, was less a voice of reason that I felt comfortable depending on and more an efficient helper for logistical stuff. I could develop a closer relationship with my “private” counselor and thus called her and texted her whenever I needed. That can really reduce stress!
Some are great, some are smoke and mirrors, and how “worth it” they are depends on how much money you have and how much it will affect your finances to pay them. I’ve done that work for many years, fwiw, though I’m more or less out of that game now (except for some siblings of former clients who were “grandfathered in”).
Whoever it is, the important point is to get some experienced eyes on the application process. Few HS students and parents can do a competitive job of submitting the applications. Maximize your chances.