Edward Niedermeyer, "Ludicrous", Chapter 9, has a somewhat lower estimate:
“In 2013, California revised its Zero Emissions Vehicle credit system so that long-range ZEVs that were able to charge 80 percent of their range in under fifteen minutes earned almost twice as many credits as those that didn’t. [...] By demonstrating battery swap on just one vehicle, Tesla nearly doubled the ZEV credits earned by its entire fleet even if none of them actually used the swap capability. [...] For the 2015 to 2017 model years, CARB created a new rule requiring Tesla to actually document a certain number of battery swaps to prove that the capability was actually being used. This development just so happened to coincide with Tesla’s half-hearted “pilot program” and its subsequent decision that its customers had no interest in fast, convenient battery swaps. [...] By exploiting CARB’s fast-refueling rules, Tesla appears to have earned as much as $100 million in additional revenue by demonstrating and hyping a system it seems to never have intended to commercially deploy.”
Source?