I believe the argument is that for something to be addictive, the user has to feel compelled to keep using it that they would take some outsized/extreme risk/action in order to keep using it. It doesn’t have to literally be about stealing copper pipes, just, any action that an ordinary person wouldn’t do, justified because it lets them keep using. e.g drug addicts will steal, even from their own families, or lose their homes because they spent the rent money on drugs. So then the question becomes: if you had to pay to use social media, are there people who are so addicted to it that they would steal, or choose social media time over their bills? If you can actually imagine someone being so addicted to it that they would do this, then you can say social media is addictive.