So the growth rate in the actual productive economy for all developed nations has been declining since the late 90's. This is because the rate of profit has been falling pretty consistently since then; though over a long timeline it has been declining since the second world war, it is just that the bump in profitability that came from breaking unions, killing socialism, and neocolonialism has finally lost its juice. Ever since 2008 the priests cough I mean economists have been reading the livers of rabbits cough I mean injecting low interest rate money into the economy to try and get things moving again by making investment cheaper. The problem is that the rate of profit on capital is just rock bottom right now so there isn't anywhere really productive for all that money to go.

Now in a socialist context you could invest all that in 'non-productive,' aka not profit generating, things like healthcare or public infrastructure, or education etc.... but in capitalism you gotta make the cheddar so it needs to be invested 'productively.' And NEED is the word here, money sitting is money vanishing, which has led to the a massive rise in what we now call fictionalization but Marx called Fictional Capital. Basically Capital is desperate for profit but cant find it so it is flowing into anything that promises a higher rate of return. And since Musk is one of the biggest and best bullshitters combined with both state and non state apparatuses giving the seal of approval and support of the company money has flowed into Tesla. It's important to remember that Tesla is less a car company and more of a financial company/regulatory arbitrage vehicle. This whole song and dance can keep going for a while, but once the underlying lack of real profit from the actual underlying productive economy all that 'Value' will vanish like hot air.

The funny thing is that the actual rational thing to do if you are obsessed with profit/growth would be to bite the bullet and invest in long term productive areas that would generate a lower rate but actually generate 'real' productivity increases. The problem is that fictional capital gives the illusion of higher profits while generating lower productivity so that is where capital goes.