There is value in a non-dividend paying stock beyond the stock market itself: ideally, the market cap estimates the value of the company if it were to be acquired, and someone buys your shares from you. So it's not simply stock market participants guessing about other stock market participants. There is an actual, valuable, buyable product being traded, namely the company itself; it just happens to be traded in the form of lots of tiny shares.
Whether the chance of an acquisition happening is sufficiently non-nil as to be worth caring about is a legitimate question. It's not completely unheard of even for tech companies (cf. Dell), but it's certainly not the norm.
Also, note that the stock market isn't zero-sum: when the value of a stock goes up, wealth is created. Nothing goes down. If a company IPOs at $10/share, I buy it at $12, and that share gets purchased for $14, nobody loses money. The original purchaser of the share made $2, I made $2, and the final owner now owns a product which the market thinks is worth paying $14 for. There may be another sense in which this activity is meaningless, but it's not because it's zero-sum.
Keyword here is "ideally". Stocks are just a very elaborate pyramid scheme in which you rely on a greater fool to buy your stock at a higher price. It has nothing to do with owning a share of a company unless you get paid dividends.
Plus what are the chances Google or Apple getting acquired? Once you go public that rarely happens.
Dell actually got acquired very recently. Google did the weird Alphabet thing. Apple had the entire NeXT saga.
It's not likely to happen soon, but unless you're a "fool" or someone who makes their money on foolishness arbitrage (which, again, you can do without being zero-sum), that's not the point of stocks, anyway. Buy a bunch and leave it alone until you retire.
Buybacks are functionally equivalent to dividends, and more tax-efficient (which is a whole other discussion). If a company's doing buybacks you're benefiting appropriately from your ownership share.
Both Google and Apple have now started paying dividends (Google has done it via the funky reverse-spinout of Alphabet, but again that's economically identical).
Whether the chance of an acquisition happening is sufficiently non-nil as to be worth caring about is a legitimate question. It's not completely unheard of even for tech companies (cf. Dell), but it's certainly not the norm.
Also, note that the stock market isn't zero-sum: when the value of a stock goes up, wealth is created. Nothing goes down. If a company IPOs at $10/share, I buy it at $12, and that share gets purchased for $14, nobody loses money. The original purchaser of the share made $2, I made $2, and the final owner now owns a product which the market thinks is worth paying $14 for. There may be another sense in which this activity is meaningless, but it's not because it's zero-sum.