How do you fight piracy and unauthorized use of our 3d models.

If you make molds for casting and create busts from polystone (as one of the options) this could become a source of some income. But there are also many nuances and in any case a separate room will be required. One printer (even if it is a high-quality SLA/SLS printer) is not enough, this won't pay off.

In addition, yes, in regards to whose busts/models these will be and what mood their copyright holders will be in, in a certain situation, of course, they can file a DMCA or try to receive compensation in other ways.

Hey m8.....I get nobody likes to be ripped off and I don't mean to be an arse and I maybe wrong but I was under the illusion that many footballers owned their own image rights? Isn't that the case?

I think your biggest "problem" is that you're making exceptionally good models that are in high demand and they are very lucrative to unscrupulous people. You may try to go DMCA route, but this will cost you money and more important your time. You will be forced to play this whack-a-mole game, that you have no chance to win. Maybe consider stopping selling digital files and start producing printed miniatures and selling them by yourself. That way it would be much harder for thieves to steal your hard work. They still can try to reverse engineering your prints, but this requires much effort and skill and the end result would still be significantly inferior compared to your originals, so that would cut theft rates by 90% at least. The downside of this of course that this would require much more active involvement from your side, but i think the revenue would increase accordingly. You may even try to find some trustworthy friend, or relative who could take care of printing, selling, shipping business for reward. I think if i would have your talent to produce that high quality content, i would certainly try to go this route instead of "gifting" digital files to whole internet.

Regarding Etsy look this https://www.etsy.com/au/legal/ip/report

You file a DMCA takedown notice:
https://www.dmca.com/FAQ/How-can-I-file-a-DMCA-Takedown-Notice