Indeed Pakistan are not favorites. Thanks for laying it out bare naked. Reaching semis will be a pleasant surprise. However, many at times, those who aren't favorite actually excel.
As you stated, Pakistan's middle is under confident. And the cause of this "under confidence" is NOT lack of exposure.
It's the lack of wrong preparation and non-existing training/coach for power hitting.
In nets, all day long they practice hitting against balls pitched in hitting zone. But in the match, they get, Yorkers, slower bouncers, on the crease wide balls, and many other deceptive delivers - against which, they have no practice and no idea how to cope?
There hardly seems to be any footwork to disrupt the spinners, there is no concept of innovation and improvisation if the ball is not in your comfort zone.
T20 power hitting is not just holding the bat in the nets and hit sixes on halwa balls all day long. No, that doesn't help. It backfires.
Body strengthening and muscle building drills must be done rigorously and religiously, so that you body and your brain opens up.
These drills help you build sharper hand-eye coordination, quick and strong muscular reflexes, powerful ligaments, and sharper vision on the ball.
And when you your body energized with all that good stuff, you jump on the balls that are out of your comfort zone and smack it for boundaries.