That and because they're considered a pest by fishing boats. Humans kill 100 Million Sharks a year, and we sure as heck aren't eating that many fins. If we did there would be a massive mercury epidemic causing infant deformity, dementia, organ failure, and loss of fertility.
A family member once had to resort to traditional chinese medicine so solve an issue - and it acctually worked, I will admit upfront - but I kept hearing how shark cartilage capsules was the best to reinforce joints and one day I just snapped and replied along the lines of "by that same logic, to obtain insulin we should be grinding pig pancreas into pills for insulin".
we used to use cow pancreas to get insulin actually. fortunately bioreactors exist and some clever people figured out how to gmo bacteria to make insulin
Is a species being poached to extinction? If so, it's probably because there's some sort of fertility/virility "medicine" derived from it that Asian men will pay insane money for.
-tiger
-rhino
-civet
-pangolon
-shark