It's possible that the older people are able to see through the facade projected by this type of person, while people their own age (with less life experience) buy into it.
As a possible example (general, not directed at you specifically since I don't know you!), your peers may look at you and see someone with self-confidence, while those with a different perspective may see cockiness. Or your friends see a tough guy, while older people perceive the same talk and actions as being a poser.
Try to find out what parts of your personality/attitude or demeanor older people find objectionable, and then really look into them; while it's possible they may be misjudging you, they may also have more insight into you than is comfortable, and if you look objectively, you may find a path towards growth as an individual.
Seeing how you are viewed by others is not always a pleasant experience, but can certainly be eye-opening. The next step, of course, is deciding whether or not you want to change that perception.