[0] https://cleantechnica.com/2016/01/15/1-large-luxury-car-in-u...
Tesla's interior is definitely spartan, with things like center console and extra cupholder set available only after-market, but that seems to fit into the story of "design the most lightweight vehicle possible in order to increase the range".
Are there reports of numerous interior-level problems, like fobs or panels or lights or switches falling off, etc.? Because honestly there's not much of "interior" there to discuss its quality.
I don't understand your doubt, there are many examples of boutique car companies who sell on either luxury or performance and sometimes both. They are all low volume adventures. There simply is more room to profit and that is attractive. Plus its very easy to feed off of pretentious people, pretentious geeks are even simpler.
Nothing could be further from the truth. Brands such as Lexus, BMW, and Mercedes are extremely profitable, because they offer cars that cost just a little bit more than a "normal" car and charge up to 30K or more for that privilege. The only constraint on the growth of these car makers is that there are not enough people who want (or afford) to pay that price just for the extras.