They don’t need everyone to buy on sale. My guess on champion Elon is it is just enough $$ to sqeek a profit for the Q. If they are taking down payments on the Y and production starts this year it’s a done deal.
Based on how the March 14th AP SW release goes, a chunk of the new FSD option price will likely be recognized which will help the bottom line. However, refundable deposits on vehicles only improve the cash on hand, not profitability.
Likewise, sales of option that are not yet fully implemented, so the portion of FSD that is coming later this year is also offset in the liabilities section of the financial statement.
The lines that track these offsets are "Customer deposits" and "Deferred revenue, net of current portion are the offsetting items".