system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can someone be shot in the brain and not die ?
gpt
Clinical Neuroscience/Neurosurg MD, PhD Candidate here.

Quick rundown:

1) If major arteries or connecting arterioles (Cerebral medial, posterior, anterior, basal or carotid) are hit, there is a high probability of death. If not, things get interesting:

2)If not, then its down to what brain matter is destroyed (And this is how researchers attributed function to area: 

Frontal lobe: Non life essential (See Patient Phineas Gage), destruction results in change of personality, executive function (higher moral, thought, rationalising and inhibition processes.

Temporal lobe ( lower side): Non life essential (See Patient: HM), destruction may result in loss of memory functions (hippocampus), loss or intensification of primal emotion (fear anger etc) (amygdala). 

If you drew a line from ear to ear along the top most point of your head, this is roughly (slightly more anteriorely) where the motoric and sensory cortex would be. Damage here results in loss of the ability to feel, or move.

Parietal lobe (top side): Non life essential, damage may lead to cognitive  changes, however its very possible that no obvious changes may be seen.

Occipital lobe (back of head): Non life essential, vision loss.

Deep brain (Di-encephalon, Mes encephalon etc.) and brainstem.
Traumatic damage here is almost certainly deadly. 

Most important life functions are breathing, arousal, and decending motoric tracts. 

3)
Lastly, infection is a major concern. High dose Antibiotic (probably broad spectrum) is necessary.

TLDR: 1) If you dont pop a major artery, 2) You can hit non life-essential brain matter and 3) Survive infection, you can survive a shot to the brain and not die.