self-defeating 
adjective
(Of an action) preventing rather than achieving a desired result; futile: courage without wariness is ultimately self-defeating the self-defeating quality of much human behaviour...
- It seems to me that the idea is rather self-defeating.
- Seldom will so much hot air have been expended by so many for such a meanly self-serving and self-defeating result.
- Rather than being self-defeating, successful players are their own best friends.
