Comfort is proportional to room, there are plenty more than 7% of the population that would refuse to ride in a windowless box they can't even sit upright in.

Remember there are two passenger compartment mockups, this is the smaller one we are referring to: http://i.space.com/images/i/000/031/716/i02/hyperloop-passen...

Unscientifically I'd bet less than 25% of people would be willing to ride in that for more than 10 minutes, much less 30-40.