Opium Wars..
.. were not as simple as the author suggests - there were a number of factors involved:
Britain wanted tea, but didn't have enough silver to buy it (the Chinese didn't particularly value gold - their currency was almost entirely silver-based. This was partly solved by the British stealing tea plants and exporting them all over the Empire - which is how India became such a major source of tea).
China had a vast demand for opium since the whole country was wracked by internal division caused by the breakdown of the Imperial system at the time. Starvation and poverty was rife - which meant that the market for opium got vast because people wanted escape from a rigid system.
The British (and French and Russians) were happy to exchange opium for tea - it was cheaper than silver since it could be made easily in India and places like Afganistan. Much cheaper than paying in silver..
China tried to stop the import of opium because it was bad for the economy to have their worker classes drugged out of their minds.
The UK/French/Russian alliance didn't like having their drug industry infringed upon so fought the Imperial Government - which the Imperial Government lost because they didn't have access to modern weaponry.
Because the mperial Government lost so much face (aka "Mandate of Heaven") more and more internal revolutions started to occur leading to millions upon million of deaths from war, starvation and brutality and, eventually, the overthrowing of the Chinese Imperial system and the abominations of Chinese civil war and external invasion (Manchukuo etc) that lead to yet more deaths.
It's really, really not a pretty story - but it's one repeated time and time again throughout history (albeit with different products involved).