When you launch your community it's fun.
You're not going to be the typical community manager, you're going to be different. You're going to be fun, relaxed, informal, cool, or anything else you decide.
You invite your friends to join you and get the community going. You participate a lot. You poke fun at people sometimes, you have long debates with people, you tell people to relax if they get too vocal in their complaints…this is just who you are.
Then your community keeps growing. The behaviour that seemed appropriate for sub-1000 member communities is causing trouble in larger communities. You have revolts against your lack of professionalism. Members leave and start their own, rival, communities (which will soon face the same problems).
This means you face a decision. You either become more professional in your approach and learn a little about community dynamics to handle such behaviour or you stay who you are and accept that this is what's going to happen in the community from now on. More so, it's only going to get louder.
You can be yourself, be what your community wants you to be, or be who your community needs you to be. All of these seem like good options and they all have advantages/disadvantages.
This is true of launching companies too. Mark Zuckerberg progressed from "I'm CEO, bitch" and referring to his users as "dumb f**ks" to a more professional demeanor he needs to attract and retain investors.
There are no easy answers here. Just be aware that who you are when you launch your community, and how you interact with members, might not be a good fit when you have a large, growing, community.