Often times users don't even know they have a fraudulent product. Some of these clones are literally just your product (third shifted) and so short of assigning bonded, single use serials (which is easy to say and very hard in practice) there's little you can do to distinguish between a legit and fraudulent product. This wastes your customer service time by supporting customers who didn't even end up paying for your product, which is overall very bad.
The people who are buying Chinese knockoff pirated flash carts, are not the same people pulling out their credit cards for paid support. Also, retro gamers are a notoriously difficult and time-consuming market to support.
This seems like an opportunity in disguise. Provide paid support, possibly after upselling the crowd to genuine product if required. Then word-of-mouth will be to the original dev's benefit; few will side with the fly-by-night cloners.
DRM makes your product less "hackable" by the customer and less likely to sustain a committed community. It's a very short sighted approach.