I doubt very much Elon will intentionally want to keep Lithium...

I doubt very much Elon will intentionally want to keep Lithium prices high - it just doesn't make economic sense for Tesla and its shareholders. The theory of Tesla being able to throw money around willy nilly is void. You don't become a company of Tesla's size by paying a premium for everything.

Think of it this way. Let's say you want to buy a house and seller has 600k on it. You've done your calculations and you think the house is actually worth 800k and will likely rise to 1.2 million in the coming years. You don't go back to the seller and say "I think you're house is undervalued. I'll offer you 750k to blow other buyers out of the water". Nauturally, you'll want to buy that house for as cheap as possible knowing the returns to be had. So don't think Tesla is a knight in shining armour, they are a business and will want things as cheaply as possible including your SYA shares if that was on their radar