A big part of an automotive design is tooling cost. For a new design this can be on the order of 200-300M (for one new model with no common parts from other older models). This is not a problem for auto manufacturers who may make 1M cars of a certain model whose style changes are minimal over a 5 year typical model style; it is a serious obstacle to market entry for a new manufacturer. Also, an established manufacturer, of which Tesla is not, can partner with his vendors such that the vendor will eat his own tooling costs based on a multiyear contract ( obviously the tooling costs will be amortized as a higher price to the part).
Assuming (and a very big assumption in this case) that the variable costs (labor, raw material, facility operating costs ) are significantly below the vehicle sales cost there is a number of vehicles where the profit rapidly increases.
Tesla is making a very big bet and both the investors and purchasers (hoping that the company will be around for product support).
This is not the type of investment that someone at or near retirement should be putting into his retirement nest egg.