I genuinely can’t tell if this is naivety or willful ignorance, but at the end of the day, it doesn’t matter.

This is in direct violation of the terms of service, and Apple invests a lot of money in keeping iMessage clean of this kind of misuse.

They control the servers, the client, certificate provisioning, hardware identification, and user identification. They can trivially trace a registered account to the point of sale and the card and PII used to buy the hardware on which the account was registered.

You will fly under the radar for just as long as it takes to annoy enough of their customers that Apple brings down a massive ban hammer.