All these long stories are quite unnecessary, you should have just gone straight to the point of what you’re trying to say, which is utility. It’s all about trust, and people make use of what they trust. When people trust something, they invest in it without fear because they believe in it. By them investing and making use of it (utility) it will start to have value. The community is what’s holding Bitcoin , if people should stop believing and investing in it, it will fall to zero.

I understand that you mean that a miner (the possible first level seller of bitcoin) will sell bitcoins only for cash; from this you mean that how much bitcoin in circulation or participating in real economy is based on bank? I guess people may sell bitcoins NOT only for cash but also services. It means number of bitcoins which are participating in the real economy does not need to be depending on bank. I mean people get bitcoins by paying cash and by working for bitcoins as well.