Because people (for the most part) aren't fools, especially on here.
People see a 600B dollar company and expect it to feel its presence in their lives each and every day.
They expect to use the thing, or their employer to use the thing or their supplier to use the thing on a daily basis like it happens with Exxon, Amazon, Microsoft, Google, Facebook, Netflix, Salesforce, Oracle, IBM...
They all earned their significance by touching so many lives and making people lives a tad better and less complicated for their users, and the rise to riches of their founders has happened in lockstep or almost lockstep with the changes and the improvement they were making in people's lives.
With Tesla you have a 600B company and Porsches (which are a rarity on their own) are still more common then them on our roads.
People are suspicious about unjustifed enrichment, always been, always will be.
"What have you done for me to deserve that amount of money? What have you done for society to deserve that amount of money?"
Such question will always come up. Musk has been able to answer to such question up to now with:
1) "Give me time!" and
2) "Wait, neat things are a-comin" as well as
3) "Population wide morale boost given by the prospect of amazing future is the real product"
People are more and more asking questions though, and he keeps answering with postponements and future deadlines, while Teslas are still less common than Porsches