If I may turn this one around - what I learned as a submissive/masochist is that I am a lot happier in that type of relationship, more confident in how I relate to my Sir or Sweetie.
In my vanilla relationships I seemed to spend a lot of time trying to make someone happy when that really wasn't what people expect. I almost feel that in a vanilla relationship the two involved are adversarial rather than partners. That was definitely the case in my late unlamented marriage.
I didn't learn anything ground breaking or shattering, just that i'm happier........ Of course, there are a lot of people that haven't learnt that yet, so maybe I'm a bit ahead of the curve. or just late getting there.