Ask HN: How effective is it to spam people who register new domains?

Every time I register a new domain I get a swarm of phone calls, spam emails, and unsolicited texts.

Does anyone know how effective this is?

I don't have any intentions of doing it, but it makes me wonder at times. On the other hand, without all of this spam services like whois privacy would be worth a lot less, so I could easily see it being worth a registrars time to fund some of the spam.