Hello student. Agreed on the point that IIM has comparatively higher fee structured when IITs and NITs are taken into picture. Here are the major reasons why IIM has this higher fee structure.

1. Salary expenses for faculty people will be really high as they are really qualified, else they wouldn't have been over there

2. Campus will be really good. So maintenance

3. Cost of teaching material they give

4, more importantly they provide scholarships to a large number of merit people

Apart from all these, you can start job with starting package of minimum 12 lpa. So it can be easily cleared off

Coming to your next question of how middle class people can afford it. Definitely it's a huge amount for middle class people. But student loans are available in many banks. Even loans can be applied in IIMs

So these days, it has become comparatively easier

Regards

Nikhitha