Am I obligated to say hello to people I recognize?

i really hate saying hi to people. for example, if i see my professor in the hallway. I don't say hello. They dont like it. When I walk into work, my supervisor didn't like that I don't say hi to my coworkers when I enter the building. I just don't know why I have to say hi to people I see on a daily basis. I find it lame, cumbersome. I don't even have any established friendship / relationship with any of these people. why do I have to say hi to them? I just don't like to say hi to people I don't have any emotional connection to.

Am I obligated to say hello to people I recognize?
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