Push to get rid of their low status traits usually comes from low status people, or parents who don't want their children to stay low status (or people who sell them the treatment).

People already use some highly harmful substances to make their skin paler. Paler skin requires doesn't give even a tiny fraction of benefits of being really "white", and side effects are far greater than what I proposed. By extrapolation if there was a magic pill you could take to make yourself permanently Caucasian without any significant side effects, plenty of black people would take it, what would increase status gap even further, until only tiny fraction of people stayed black.

Nobody says blackness is an illness now, because you cannot change it. If it ever became easily changeable, that would change very quickly. Of course we are unlikely to see this being tested, as such procedure seems unlikely to occur.

Here's data on how being "White" as opposed to "Black" drastically increases your mate selection opportunities. There's earnings gap, lifespan gap, larger chance of being a crime victim when you're "Black". It's naive to think that people would stay "Black" voluntarily if it was a matter of choice.