The financial impact of spam alone is estimated to be tens of billions of dollars annually. There are many non-financial impacts that extend far beyond "annoyance"

Spam is annoying the way polluting the ocean or mosquito bites are "annoying". I don't personally see a lot of ocean trash, and nobody I know has ever died from a mosquito bite, but there are massive harms with worldwide impacts caused by both.

In my view, the refusal to accept responsibility and the willingness to repeat and continue his offenses without any regard for the harm it causes suggests sociopathy, or at the very least narcissism.

Spam is definitely bad for society. So if 1 piece of spam is bad then a billion spams is 1B times as bad. That's a big factor. Probably getting near axemurderer levels of social damage.

Axemurderers have an expiry (the day they die/are put in prison), spam does not.

I think your estimation is grossly underestimated too, Nigerian prince scams trigger (insufferable) workplace discussions which take 5 minutes or longer, for upwards of 5 people, spam that causes people to spend money they otherwise wouldn’t increases the wealth gap, impacting lives for generations.