So in other words, if Tesla does everything right, executes perfectly on a global scale, suffers no major hiccups, and they grow their annual free cash flow by tens of thousands of percent from their current position, they'll finally justify their valuation and your ten year return from a current investment in Tesla will be 0%, not adjusted for inflation.
The bull case from here is thinking that Tesla's valuation will permanently stay in the upper atmosphere for decades to come, but at some point, the growth rates slow. There are only so many automobile purchasers on our planet, not to mention the competition which is picking up. My bet is that Tesla does not get to $70B in FCF by 2030. I also don't think the market will give them a 30x sales valuation forever, especially as their growth rates eventually begin to slow. They've already saturated Europe and are heavy into the Chinese market, and of course, their US + Canada market penetration goes without saying.
Maybe Tesla goes back to a normal valuation via a $3T market cap, giving current holders a great return (so long as they cash out at the peak). Who knows. But long term, I don't see how they justify their present $1T market cap, and as Ben Graham famously (and rightly) quipped, in the short term, the market is a voting machine. In the long term, it's a weighing machine. EVs are "in" right now, and they're getting lots of votes, but in ten years, EV manufacturing will be as boring as ICE car manufacturing is today and the industry's valuations will be weighed on its own merits.