They had, and still have, an immense first mover advantage in the internals of EVs - look at some of the mechanic analyses/teardowns of Tesla internals and it's a night-and-day difference against other US EVs in terms of engineering around reliability, simplicity, and efficiency.

But, they never actually followed that up with truly improving the the vehicle interior and all the other bits of build quality, and then doubled down with the Cybertruck, which has brilliant internals wrapped in bodywork that's impossible to clean and with trim that will literally fall off in the wrong weather.