The embedded assumption is that current demand is sustainable, rather than simply a reduction in a multi-year fanatic backlog.
Embedded inside that assumption are a lot of assumptions about ramps in production with consistent quality and finish, and lack of EV competition.
I personally disagree that Tesla can maintain production and quality at these levels without needing more financing, but the verdict is definitely not in yet.
https://www.bloomberg.com/graphics/2018-tesla-tracker/