Revenge: Great Motivator?

One of my fave people in the world "R" messaged me the other night. We have been friends for almost 16 years and we know each other so well, it's crazy. Between the two of us, we have been through so much. She is a person I love with all my heart and I know she is friends with my unconditionally. She has no ulterior motives. She is a true bestie! She has just gotten into dating and is having a hard time. I try to cheer her up by telling her marriage isn't a cake-walk either. She at least gets a laugh out of that.  R: Soooo wanna laugh?
Me: ALWAYS
R: I just found out X got a new job. I almost went there on a date. I went on a first date with a new guy at the Olive Garden in town. X has a job next door. He works at California Pizza Kitchen. Totally almost went there since the wait was like 45 minutes.
Me: OH GEEZUS ON A CRACKER!! HAHAAAAA!!! (Yup. Sometimes I have just the right words to say.)
R: Sooooo close.
Me: That would have been epic!
R: I would have died!
Me: Had I been there, I would have peed my pants in excitement. (Again just the right words!)
R: Why would you be excited?
Me: Because he was such a *expletive* that he deserved to see you having a good time with someone else! The awkward ex run-in is a right of passage.
R: I doubt he would have cared. He would just bring up that we had a bet. I told him he would end up with a GF before I had another BF. I won. He already got a GF. I'm collecting my dollar but not before I lose more weight. Part of me is doing it because I have time now.. the other part wants him to eat his heart out when he sees me. Revenge is more of a motivator than health I tell ya.
Me: It is a motivator to live a better life so the other person wallows in their misery. It feels awesome at first then you get over it.

Story: R's X unceremoniously dumped her for no reason. He just ghosted. No slow fade, no one message here and there, nothing. Just *POOF* gone. He didn't even tell her either. He just changed his relationship status on facebook. Winner, right? Classy for a 28yo guy, let me tell ya! It was her first serious relationship and it hurt her a lot. She is not the type to talk about her feelings too much, but I know it hurt her a lot. I told her the guy was obviously a loser and she was better off.

Revenge can motivate people to do strange things (read the news!). A woman's mag claims you should look hotter for the next time you see an ex. Why is that? If your relationship was based on looks, it wasn't a real relationship in the first place.
The only thing that should motivate a person is their inner voice. If you lose weight or change your life for someone else and they don't notice in the way you want them to, what then? Like so many things we humans turn to, it is a temporary high. How does a life change really benefit you in the long run if you don't have the outcome you expected?
Thoughts, anyone?