You're right, the Bitcoin price is decided by the market.  So therefore we analyse the market and what other people are going to do because not everyone acts unanimously and buys Bitcoin at stupidly high prices because we tell them to.  The market acts primarily in its own interest.

In the spirit of the free market, this isn't true.  If banks or governments wanted to, they could easily control the Bitcoin price.  All they'd have to do is buy loads and dump it at super low prices - they have more than enough money to do it.  It's only about how much money you have and in reality it's not a community decision - if you build a collection of 20 people who own 0.2 Bitcoin and don't understand any basic economics, they won't have any significant impact on the market at all if you tell them to buy or sell.
Hang on, didn't you just say that we control the Bitcoin price?  So doesn't that mean that it's "worth" exactly as much as it's worth right now, since we control it?