A BTC is not notional nothing. What determines the value of a thing? The market does. Not you. The market. And the market has determined that BTC has value, and that's been true now for 16 years and counting.

At any rate, to the tokenized stock example, if you are purchasing a tokenized stock represented by a company such as Robinhood, it too is a debt in that the token is exchangeable for the underlying.

This is an even higher level of guarantee than, say, an options contract, in that the reserves are provable. It does, of course, involve trust in the intermediary, just as your bank balance does. But at any rate, this financial technology is an expansion of what isolated databases provide to the market.