The people who make it don't want it, the people who buy it don't use it & the people who use it don't know. What is it?

A coffin.

Unstretched Cocaine

Game over!! Unless of course anyone else has a puzzle to offer.

The people who use it don’t know what?

@Aster We’ve moved on dear, the answer was indeed a coffin.

@Aster They don’t know they used it.

Fluoride.
Highly toxic waste byproduct of aluminum. The people who make it don’t want it, the people who buy it surely wouldnt use it & the people who use it don’t know What it does to them.

Leaded toys made in China.

They don’t know they use it? sorry; I’m drawing blank as usual. How can you use something and not know you’re using it?

@Aster They are dead and don’t know anything. they are in the coffin.

For my nonstandard answer: Little kids have no idea what lead does to them.

@Odysseus I refer you to American Dental Association re: public safety of fluoride.

Meatloaf.

XS-size condoms.

Bubble wrap. people hate to make it. it smells terrible. people who buy it soon discover that it is more troble than its worth and people who do use don’t know the dangers it presents with their pets and choking.