I love a lot of things, and I'm pretty much obsessive about most things I do, whether it be gardening, or architecture, or music. I'd be an obsessive hairdresser.

This quote means that the speaker loves many things, and when they are interested in a certain activity, they become very passionate and dedicated to it. For example, if the speaker were to become a hairdresser, they would be very committed and focused on learning the craft and perfecting their skills.