If you got a company named T with a total of 100 shares. Now they want to raise money and someone is willing to pay $10 for a share. You get a market cap of $1000. They create the extra share and someone is still willing to pay $10 a share. Magically they are worth $1010.
Now T is selling the share for $10 and the next guy willing to buy only wants to pay $9. Magically the market cap drops to $909.
Right now many Tesla share owners believe they will get rich by holding. Someday all of them might realize at the same time everybody is holding and decide to sell. If that day is tomorrow it will not be 600B actual dollars changing ownership.
If Tesla would raise 25% market cap they would destroy the stock. I guess it might take at least a month or more for the market to absorb 1% new shares.
Right now we have a market where a lot of people sold and the same or new investors freshly bought again and are optimistic. We got many people buying and not so much selling. Market cap is in a way a to simplistic metric.