I know this type. I've seen them often enough. They revel in being obnoxious: but not towards the rich and powerful, to whom they fawn. Always towards the weaker and the poorer: towards people who don't have their privileges, such as access to private medical care. They think it's funny and daring.

Though we can't be sure in any one case, it's such a common pathology among certain types of privileged people that I suspect it might be transferance: the redirection of trauma and self-hatred. What presents as mocking self-confidence could reveal deep insecurity and/or externalisation of fear.