Im no rocket scientist, but the underlying assumption of speed being the only input seems incorrect. You can go slow or you can go fast. The energy required will differ but going slower will be much nicer on the human blobs 😬

This is how science works. You question everything, assume nothing, trust no-one.

My son is using your flat-earth arguments on his friends in high school

It’s very compelling if you don’t understand anything about physics. The speed of an object can vary depending on the coefficient of friction. Ie shooting gun underwater vs top of Everest both air and water are both fluid with different density. With elevation air density decreasing and friction decreases, once you reach the edge of the atmosphere there is close to zero friction the same reason you cannot breath up there. Then you have relativity but if you can’t grasp density and friction then you probably won’t grasp relativity.

But what if you burn more fuel rather than going fast? Though the Astronauts just sitting there unaffected by g-force or vibrations is weird af.

The rocket looks like it’s going slow because it is actually going slow. The initial thrust to weight ratio is low, resulting to only 0.2-0.5g. Only at higher altitudes when the weight drops, accelerations of max 3-4g are achieved. That’s for the obvious reason of not crushing equipment and the astronauts. Also, rockets move in 3d space, a lot of the speed is also horizontal. Comparing a full speed, close up object, moving horizontally, to a rocket taking off is child level logic.

How can someone be so stupid

agreed, it's hard to imagine being a NASA believer