Miner's profits have to do with the stability of the network and the demand for bitcoins. At high bitcoin prices, their return is better than when the prices are low, other things (thing, mining difficulty) being equal. It's much like gold mining: it has become much more profitable of late because the difference between extraction price ($250 to $400 per ounce in most places) and sale price (roughly $1,500 per ounce) is how much the miner takes home.

Decentralization increases this price because it makes bitcoin sound. If there's no one door to knock down, or one person to subpoena, the cyberpunk currency can robustly survive losses in its network and still have enough computing power trained on it to prevent attacks.