I'm still really new to options but I'm trying to understand this concept of assignment.

Let’s say I’m short a call of Microsoft at a strike of 80 set to expire in a quarter. Microsoft surges for one day, going up to 86. Someone long a call for the same option exercises early. It’s randomly assigned who has to physically settle with this buyer. And so as an option seller, you can’t guarantee you will hold the option until expiration, and you can be randomly assigned to someone who wants to exercise early? So you're taking the risk that you will be randomly assigned someone long the same option who wants to exercise early? How is this fair, as theoretically different traders short a call for the same strike may receive different profits based on if one is exercised early?