I'm currently single and it's not so much that I'm against dating and relationships at this point in my life, its that there's a lot of things I want to do before I begin that phase of my life. For example:
I want to know that I can truly do things on my own and I want to spend at least some part of my life living independently (no family, no SO). I want to travel without having to worry about fitting into another person's schedule. I want to go on adventures and have fun with my friends before they all settle down into married life.
Also, the implications of that last paragraph really sum up why I feel like I need to get these things done before I'm ready to settle down: my parents have always advised me to wait until I'm in a good position before starting a family. I remember the poor days growing up, and I would want to avoid/minimize that experience as much as possible when I start having a family of my own.
So yeah, I'm not against dating and relationships right now, it's just that there's some things, big and small, that I want to do first.