Why do people who see you are very concentrated and in the middle of something make a point of trying to interrupt you

With some kind of mundane bullshit the next time someone does I'm going to start some fucking shit with them

My friend Steve used to do it all the time if I was doing a hard math problem which takes total fucking silence to do otherwise you have to start all over with remembering where you were don't know why I brought this up I just needed to vent that because it happens over and over and fucking over