This is where you fall apart. It's an equal and opposite reaction to action inside the bottle, so no force is applied to move the bottle rocket from inside, because it's like Samson pushing on one pillar and against a impenetrable wall, the pillar being the water and the wall being the base of the bottle rocket, or upside down bottle.
I'm struggling to understand your point.
The pressure within the bottle isn't creating a net force because it's pushing equally in all directions, but the ejected water is. In a closed system (ignoring what happens to the water after ejection and ignoring gravity) the centre of mass of the system (bottle + water) wouldn't move. Since water is shot downwards, something must go upwards so that the centre of mass stays in its position.
The mass of the ejected water is what moves the bottle vertically, coupled with it's base pushing air out of the way.
Yes, that's right, what's the problem here?
What you have been told, is a lie.
You better let the world know then.
Thrusting against itself. It's like blowing your own sail or trying to paddle your bath out of the bathroom by dipping your oar into the bath whilst you are in it.
And rockets work like this do they.
Have a word will you, Mr physics.
It's nothing like that. When you blow into your own sail, the air is deflected back at you (in an ideal circumstance), creating a force in the wrong direction for your boat, thus cancelling the force you've applied for your boat's movement.
If you had the rocket thrust its propellants into a wall that's attached to itself, then the rocket wouldn't go anywhere. It's also similar to trying to lift your own chair while you're sitting in it.
Do you seriously think that scientists haven't thought this through? Trust me, you are never going to even come close to debunking mainstream science, because anything you can think of (as long as it's sane, logical, and scientific) would have already been thought of. Newton's laws of motion have been put under severe scrutiny for centuries, and they've held up to the test.