The customer accepts the terms of service on Monday, breaks them on Tuesday, says they mean nothing?

Of agreement in principle only some points:

The comparison with SPAM is not valid because UCE is illegal in many jurisdictions, while encryption is not illegal. In the best of cases, it is questionable in some limited areas around the world but not against the law. Certainly not in most nations like the United States, Canada, most of Europe, etc.

As for customers who try to argue that it is "a server" not a cryptocurrency, let's start with a question? What is the problem with extracting cryptography from your server? As above, it is not illegal. It's not UCE, it's not child pornography. So what is the problem? (I'm not arguing with you, just playing the devil's defender for a second ..)
If I'm putting myself in their place, the problem is the use of resources *. A CPU that is too high with time or an IO held too high or similar. Yes?

So when you suspend, instead of citing cryptoserver or plex or whatever (this is where they make their argument), quote the USE OF RESOURCES.

"Sir, you were suspended for abusing system resources as described in our TOS." As shown here, your server used a CPU xyz for 1 hour and the limit abc ".

This is unambiguous and no argument can be made. Paypal will understand and even the credit card companies will understand. You are more likely to deny the return. This is also a much stronger language to respond against negative criticism with imo.

The other side of the coin is to consider that, instead of suspending it, you have two options:
a) Accelerator. Hard accelerator. Accelerator without mercy. If the TOS says that you do not do X and you do X, then the TOS can say WHEN YOU DO X will accelerate your VPS to the ground and then the VPS to the accelerator. Not suspended. And as soon as the use of the resources is back online, the server continues normally. Just be VERY in front of the limits of resources. If you can automate it, it is better that it is not a "judgment" call. There are no humans involved.

b) Migrate them to the "bitch" server. Reserve the oldest anemic server (hardware) you have and migrate all the TOS circuit breakers there. Like regulation, but organic, let resources pigs and whores fight with each other for CPU and IO. May the best bitch win. The downside of this is that they will stop thinking that their "servers stink" but, as mentioned above, you can make it clear when you migrate that they are being moved by resource abuse. And again, better if it is automated and it is not a call for human judgment.

The hoarding of resources is incontrovertible. It is irrelevant if you like "plex" or "bitcoin" or "zerotoken" or the currency of whatever the flavor of the week is. Each host on any part of the shared hardware has limits. Period.

Only my 2c. Gastalos as you want …