"Who on earth would actually sell any Bitcoins right now" (spend and sell have the same effect)... yet in the market, there's a seller in front of every buyer.

Regarding stuff being priced in BTC, prices are falling when BTC is rising. Who doesn't like lower and lower prices?

That pizza used to cost 50,000 BTC, it's only 0.0003 BTC today!

Bitcoin is a deflationary currency.