Why are the $1,000 deposits for Tesla Model 3 refundable?

It is rumoured that Tesla has taken pre-orders of 200,000 for the Tesla Model 3. However, why is the $1,000 refundable? How many of the 200,000 will actually buy a car? How many have paid the $1,000 just to show friends they are on the list?

I can only assume this covers the company in case they are not able to deliver on time? However, the company will have access to a massive amount of additional funding in the short term!