So if everyone else decides to exit a market, your sole product becomes illegal?

Markets are typically broader than a single product and in the history capitalism has this actually happened?

yes. ASML.

There is always a first entity to start any market and always a last one to exit it. So technically it happens thousand of times per day. Surely it’s not illegal. I could decide to sell a completely useless crocodile-alike decorative robot companion for programmers that includes a powerful GPU that finetune your toy language model of choice or mine crypto when the GPU is not used as a robot. It would be silly, and I’d never actually do it, but surely the FCC or justice department wouldn’t have a problem with it.