Very nice observation. In theory it's true, but I don't fully agree. Most sellers currently are miners. And when selling they set price that they think is profitable for them.
Considers: 300 bitcoin per hours. In a 24 hours period, 7,200 BTC are generated. That mean that the market must move 7,200 BTC a day.
I don't think it must. I mine, but I don't sell.
Btw, I think I just found a chain that was missing in my head. Here it is:
If you want to have bitcoins, you can buy them, or you can mine them.That's basically it. Verbose version:
Having this choice, you could also hire somebody to mine it for you. But either way, you have to spend money on mining or on buying. If mining gets more expensive, then less people will go for the second option. So that creates more demand, and as you noticed supply is constant, therefore it should push price up.