It is all about liquidity. If people are willing to buy your bcc at the end of the day, you can get out of it, if not you will just be stuck with a bunch of very expensive bcc tokens. How is this different from any other thing.

If people are not willing to buy the coffee you have just produced you are stuck with it and you are willing to sell it for less. If people will be willing to sell it for less than so be it.

If you think the numbers are not possible so there are two options here, either people will accept less money for their bcc or there will be an extreme devaluation of the USD (Germany 1923). Hyperinflation of the USD anyone???
Feel free to check this video and this post https://steemit.com/bitconnect/@cicnos/bitconnect-how-does-the-trade-bot-operate I wrote about how this could all work. I'm not offering my referral in neither. I'm not defending the system either. I'm just trying to show that at the end of the day what you call unsustainable is actually quite possible when you look at the bigger picture. The continue growth of cities and the exploitation of natural resources is unsustainable, these are finite systems, but the ever printing of the dollar... well we have been doing that for quite a while now. And that won't stop now.