A 'security' consultancy posted an article on LinkedIn on 'critical security vulnerabilities' they found on the web app from a company I worked at. The company hired them to do an assessment. The most critical vulnerability was a bug on a login page preventing registration.
So not only does cold calling work, bad-mouthing on social media seems to be a viable strategy. I'd have blacklisted them.
Well that's the thing, isn't it? He (and others) may be thinking "Hey! This worked!". But he has no idea how many potential customers looked at LinkedIn and say "screw this guy" and will never do business with him.
These people live in a different reality than the rest of us, one they've likely taken steps to convince themselves is true so they don't have to feel bad about their actions. I met someone years ago that was basically a professional email spammer that described his job as marketing and sending newsletters and was convinced that people were OK receiving spam and that he was providing a service by spamming garbage to people who didn't sign up for it.