The greatest, and worst, moment in British history?

There is a vast chasm between selling opium to a country to extract money (specifically to lower the huge trade deficit with the celestial kingdom) and plotting to overthrow it through narco terrorism.
Any history on the matter will happily affirm the former and rubbish the latter. Britain not planning for any war with China on the matter, least of all to grab Hong Kong - that being purely incidental and a byproduct of the war not planned.

So why did Britain accept Hong Kong in exchange for peace?

Why wouldnt they? That doesnt mean they orchestrated the opium trade and the war to simply nab the island

I thought you knew your stuff.

"In order to stop this, the East India Company and other British merchants began to smuggle Indian opium into China illegally, for which they demanded payment in silver." - https://www.nam.ac.uk/explore/opium-war-1839-1842

Apparently better than you, that doesnt say Britain started sending opium to China as a plot to nab HK, did you even read this

East India Company was the United Kingdom you dum dum.

If this thread was a boxing match the referee would have had to stop it by now.