1. It wasn't really a niche I was interested in
2. I didn't feel I was qualified to dole out advice
But later, I thought about it more deeply and I think there was a third and, perhaps more important, factor.
I didn't want the responsibility.
Having a list is a lot like being married. You are developing a long-term relationship and you are constantly being evaluated and/or judged. The main difference I saw between marriage and a list is that a list is like serial polygamy. Trying to be married to thousands of different people is a balancing act that will drive you insane, if you let it.
Now, I am comfortable with the idea of listbuilding because I have discovered a niche I know a lot about and I am not going to tear myself apart trying to please people. I know where I stand and if people are not happy with me they can always unsubscribe.
So what makes/made you hesitate about building a list?