Or the reality that there is lot more options so people gravitate towards them. And brand loyalty might also be a thing, of which there is lot for also other brands.
Tesla still has some advance in terms of autopilot (in the US), but for all other things, it's an electric car with a great software but a rather low-quality hardware finish if to compare with other brands like Mercedes.
It's worse than that. Nvidia has a moat (deployed software and the open source software ecosystem) that buys them at least a few years, even if a well-resourced hardware peer appeared out of thin air tomorrow. Tesla has nothing like this. The cost of switching away from them is negligible, and they have half a dozen extremely well-resourced competitors.