With Filecoin I think what happened in that conversation was that to Juan it wasn't a big deal, it's just one of the things possible in the IPFS paradigm. But since crypto currency is all the rage these days, and this being YC, he was being lead to talk about the money side of it, but I don't think he really gave it much thought, other than that Filecoin is a neat way to trade storage without any paper/fiat currency, across country borders, etc.
To put it another way - IPFS is the thing. Filecoin is just a side-effect. But in our present times, Filecoin is worth actual millions, while IPFS is just a protocol. But it's clearly a fluke, the most important technology/idea here is IPFS.