The guy who invents a mod, particularly something difficult to build like an EV conversion or a boattail, will never recover his costs in terms of mileage when you consider R&D and installation time, the same way the OEM's do. It's only the guys who follow him, and don't have to think through the mod and test and tweak because the inventor has already made the mistakes, that are going to see real savings.
Again, though, I don't understand why you seem to think it's a bad thing that this is so. The inventor has the satisfaction of achieving a performance goal and the long term satisfaction of many people giving the ultimate complement by adopting his mod... and if he's lucky, inventing a patentable mod that he can sell to the OEM's and REALLY recover his costs! Although not in the way he originally envisioned...
For example,
these guys weren't worried about costs. But they're making money now selling conversion kits.