Competitiveness is fine, it can be stimulating, but being an actor and pursuing work in this industry is already tough enough. If auditioning was a sport it would be more like golf where your biggest competition really is within yourself, only in this game the rules are not meant to be objective or fair, and there could be a million reasons why you may or may not book that job that have absolutely nothing to do with your performance. So, I think that if you surround yourself with people that are constantly competing with you who have a hard time saying "Congratulations!" when you book a job and they're playing the comparison game nonstop, after awhile that's gonna take a toll.
Also I think a healthy relationship in this industry is one that is not going to cause you or encourage you to cross your own boundaries. I am not of the belief that as an actor you have to be willing to say yes to everything. I recently did a video on the channel on knowing your boundaries and being willing to say no (see "Time Away & the Power of No", Dec 2021). As an actor you do not have to lay yourself out flat and be wiling to do anything and everything to prove yourself. No, no you don't! You are a human being first, and you have boundaries.
We all need people in our lives who are going to shoot straight with us, we need honesty, we need accountability. Someone who is willing to be honest with you - even if it's uncomfortable - but in a way that is edifying, in a way that is stimulating, in a way is inspiring, and in a way that is encouraging. These are the type of healthy relationships that I think help you as an actor, and especially, having that person in your life who is truly joyful and celebrates with you when you win and is genuinely happy for you - that is a healthy relationship to have in this industry - and in life!