MIT MFin MIT MFin Interview Invite

there's only about 15-20 in this forum that have been called. Not saying no one else outside hasn{t, but I would definitely chill and not loose hope.
What I also don’t get, why are some called and others not? (Assuming that people get in without receiving a call)
This year is especially difficult for grad school application bcz a lot of people deferred last year and many decided to go back to school due to the pandemic. So its exponentially difficult to get in. I kno someone from a top university in China 3.9 gpa 336 gre and hasn't got into any school yet