For the 5km chimney it needs to hold on 500km/h winds. For scale a category 5 hurricane is 250 km/h. Is it even possible to have that kind of structure with existing materials?
I'm not a real engineer, but most structures don't have the ability to flex like this tube could.
Rich Homie Quan couldn't even flex like this tube could. Making really tall stuff is hard.
While I am generally skeptical of this idea, 500km/hr winds occur at much higher altitudes - the force is much less than it seems because there is much less air doing the pushing. If a human can get to the edge of space and freefall safely, I imagine that will not be the sticking point.
The falling human is free to move with the wind. No shear forces. Unlike a tower attached to the ground.
They are proposing a fabric chimney. For sure that has its own challenges, but shear force isn't as much a problem, from I would intuit the setup to be.