Except Tesla hasn't built an affordable car yet. You could argue the same for Dyson's vacuum cleaners, which are still premium devices much more expensive than regular vacuums.
1. Build sports car
2. Use that money to build an affordable car
3. Use that money to build an even more affordable car
4. While doing above, also provide zero emission electric power generation options
Tesla is on schedule with their strategy; they obviously can't just jump from step 1 to 3. We'll see if they can move from step 2 to 3, but their success from 1 to 2 is super promising IMO.
This is actually a very common strategy for introducing new technology to the market. It seems like this strategy was applied for the initial iPhone as well, as it originally cost $600 (far more than any other phone on the market). Pretty soon it was $400, and then after a generation or two, you could purchase one for $200.
Except they have. It's just that the costs are mostly up-front vs over time as with ICEs.