My friends say that they want a 98+ so that they could close their high school lives on a high note, Some of them feel that if they don't get over 98+ atar they've failed school, Some of them are just competitive so they like to rank themselves against others, Some of them are literally just smart and I can't see them getting below a 99.95. Personally, I fall into the "below 98 is pretty bad" group (not saying that it is actually bad, but just for my standards lol) also because most people I know go to tutoring which is expensive and we kinda don't wanna waste our parent's time and efforts so yea lol.
Oh yea some people might also want to try out for Scholarships and Co-ops for university which often requires atars in high 98+