Earlier quoted context omitted.
“If you lose half your brain, you’re probably dead, and if not, you’ll be drastically impaired the rest of your life.” Depends. Patients who undergo hemispherectomy at a very young age can recover remarkably well; a testament to the incredible plasticity of the developing brain. https://en.wikipedia.org/wiki/Hemispherectomy In adult brains, yeah, it’s a very different story. See also: stroke. Honestly, you’re both ri…
This is probably an example of an "exception that proves the rule".
https://en.wikipedia.org/wiki/Henry_Molaison#See_also
Mind, these are the 'famous' people.
My google-fu isn't super great here, so I've not sources, but I know of a few cases of French postmen that 'suffered' from hydranencephaly, were married, with many children, and otherwise 'normal'. It's not super uncommon that people with otherwise good balance but who cannot ride a bike also 'suffer' from a lack of a cerebellum.
The wiki article on hydranencephaly is SUPER wild. Take a look at that picture of that baby! Though it is typically lethal, there are cases where those affected survive into adulthood