I can't believe what I'm reading, you people could convince yourselves
that the earth is flat.

The problem - You have 3 doors and choose 1. Then Monty Hall removes
one of the wrong answers from the problem. So you have TWO possible
outcomes - either stay or switch. One of these is the right answer
so you either get it right or you get it wrong. 50% You don't have
6 possible outcomes, or 4, or 3 or whatever you're all saying. You
either get it right or wrong (stay or switch) 2 possible outcomes with 1 correct answer, that says 50%.