>Space - We've been misinformed about space to keep us trapped. What if stellar parallax has some fundamental error and stars are nowhere near as far away as we've been told?
Because it is not solely determined by stellar parallax.
For example, we now the universal gravitational constant that correlates mass of an object to the force of gravity based on just behaviour of objects falling on earth.
=we know the rotation period of the earth around the sun
=we know the mass of the sun
=we know ball park figures of the mass of stellar objects
Therefore the galaxy cant be an order of magnitude smaller but remain in a stable rotational motion.
You can make a similar argument using the brightness of stars in the night sky btw.