It was a *gamble*, though -- everyone who reserved knew the tax credits might start to phase out before they got their car (seriously, there were lots of discussion of this on all the car websites).
The only people who would do this are people who would buy the car *regardless* of whether they got the tax credit. I mean, the only way you can get the credit is if you accept and drive the car! And you have a chance of handing Tesla $1000 for two years just to get NOTHING. Very few would do that.
The idiot who shall not be named described it as an "option" on the $7500 tax credit. I do some options trading -- that's an expensive option.
The $1000 deposit is refundable whenever you want.
The main way to maximize the chance that you can use the credit is to put down the refundable deposit.
The only cost of the refundable deposit is the time value which is nothing. And some credit risk which only short sellers think is anything material.
Other threads project with detail how the credit will be phased out and they predict with clear reasoning logic and evidence that significant numbers of model 3 buyers will benefit from the credit.
At least those who were smart enough to put down the refundable deposit early enough will benefit from the credit.