Which makes me wonder how much these guys spent per phone number. If you figure you can use a phone number maybe 2 or 3 times per service before it gets blocked they could create literally millions of accounts with this operation across various services. I don't know what the black market value for a Gmail, Facebook, Instagram, Reddit, HN, etc... account is, but I suspect it is more than the price of a SIM card.

About a $1 for a Gmail, IG etc these days.

I've used this before when I need to create an IG for a work project without wanting to link it to a personal number:

https://www.textverified.com/verifications