Study gold. It does not have an appreciable real economy, and measuring its flows is difficult and obscure based on the paper gold charade.
Same with XMR, or BTC. The market cap is based on the willingness of people to hold. As with gold, I actually could not care less if it is directly spendable. Perhaps I have to say it again, since it is important: I could not care less if I can spend my BTC/XMR on stuff.
As long as it is alive, it has value, and then it has a price, and then I can hoard/dishoard it. That's it. By definition, I can always do what I want. If it is better value to convert XMR to another form before spending it for goods/services, it is just a practicality. If I can pay directly, it is just a practicality. Either way, it does not really affect my propensity to hold, and holding (alone) gives money its value.
I believe the qualities of XMR are such that when people just learn about it, they are willing to hold it. The more they hold, regardless of wallets, regardless of spending opportunities, the higher the market cap.
The "store of value" market is the ultimate prize. Once you capture it, as gold has, you don't need any economic activity at all. Then you become king.
But we're not anywhere close to that with bitcoin or XMR.
I agree that the real economy of a commodity (or fixed supply asset) is a poor predictor of price. But it becomes important when people are universally, irrationally dumping their gold into the ocean, which is what is happening with cryptocurrencies currently. This is the only time that I look to their real economies to judge where the "quantum foam" basement level is. XMR needs people to hold it, but it will always be held by someone. There's no question about whether someone's holding. The question is how many people want to hold versus the available supply. If no one much wants to hold (besides those who are already holding), we must look to those who need to hold.