Okay, but that's not what he's claiming. He's claiming that NPV is derived exclusively (and rationally, and perhaps clairvoyantly) from the future sum of dividends.
The value of the stock is the current estimation of that npv. How it is estimated is irrelevant. It is the group estimation across all buyers and sellers.
I feel like you're taking part in some unrelated discussion. This entire discussion started because jcampbell claimed that NPV was derived from the sum of future dividends. (Actually, he claimed that stock price was NPV of those future dividends.) No one here seems to be disputing that stock has a NPV. They're disputing jcampbell's claim that NPV is derived exclusively from future dividends.
You're arguing against a claim that no one is making.
The sum of all the cash flows related to the stock (discounted for time). Dividends are not the only factor there. For most investors and most stock, the future sale price (i.e. when I sell my share) is the major factor, and any dividends are a minor factor.
When you sell your share, someone else buys it. How do THEY value it?
someday in the distant future, the stock is going to pay a dividend. cash flows are what enable them to do it. eventually the company has nothing to do with the cash but to pay it out.
They might value it by expecting dividends, or they might value it by expecting the share price to grow, or they might value it by expecting a profitable acquisition. Hell, they might buy it hoping the company will liquidate and disburse its holdings. Dividends are only one possible payout that can come from buying stock.
You and jcampbell are making the same mistake. You're looking at dividends, seeing a reasonable explanation for stock pricing, and then simply asserting that what's reasonable must be true. But it's not true. A ton of things factor into stock pricing and value. Some are rational, like attempting to estimate the future value of dividends or an acquisition. Some are irrational, like assuming that upward trajectory will continue "just because". And others are in the middle, like believing that timing the market is possible.