Re: What do…
The doctor (in my humble opinion) is not entirely careless as he fancies himself to be. 
I’ve seen instances on the forum where he has cared about how he was perceived. He apologizes when he’s wrong…a beautiful (but rare) quality in our times…so it shows that he does have the ability to introspect. Not everyone can and many who do will suppress it.
Life01,
That’s a difficult question to answer. When it comes to matters that you know will not affect anyone else’s zaat in any way, is not an injustice, nor a transgression of someone else’s rights…then it’s okay to not give a damn. Whether or not one is religious also plays a role. If you’re religious you will judge your actions (even the ones that don’t affect others) from that perspective…is it halal/haram/jaiz etc. But having that ability to introspect about your own actions and even how others perceive you is necessary because it enables self-growth, to make amends, to maintain relationships, to better your duniya and in turn your akhirat.