> I think the snake oil claim is in regard to VPN companies marketing themselves as a security product

Considering that confidentiality is a vital component of overall security, it's not necessarily unreasonable to describe a VPN as a security product. Of course, it's not the panacea some companies claim; nobody's "surfing the web in full security and privacy" with just a VPN service.

Similar to cryptocurrency in this respect. People would often tout nebulous benefits for hypothetical legitimate use cases, when in reality they were only ever really good at ponzi schemes and conducting illicit transactions.

That argument only makes sense if people don't really understand what a VPN is or what it is actually for. They're somewhat of an expensive and complex thing that usually noticeably slows down your internet connection... I doubt many people are buying them because they think it protects them from identity theft or something. I haven't seen an ad on the internet in a decade (thanks uBlock) - so I'm not sure if there's some ubiquitous misleading ads I'm missing.