alt Hacker NewsIt is how bitcoin is designed to work, but it also shows very directly how proof-of-work systems can never scale to be the global monetary replacement its boosters push. If the opposite happened, and the price for some reason sky rocketed to, say, $1 million per bitcoin, it would necessarily mean that it would induce more miners until the difficulty and consequent electricity cost (regardless of the efficiency in electricity generation) also would rise to the neighborhood of $1 million per coin. At the point you're far beyond "Argentina levels" of electricity and getting into "Europe levels" of electricity to run the network.
The electricity demand (and here I mean the overall cost of the electricity, so improvements in $ per kilowatt just mean you need to use more electricity) in proof-of-work systems fundamentally scales linearly with the overall valuation of the coins in the network, which means proof-of-work systems can never scale as large as their fanboys would have you believe.
While I don't disagree in general, there are a couple gaps in your reasoning that weaken the argument:
Adoption doesn't necessarily correlate completely with price. Price can increase without much adoption, due to speculation. In theory, adoption could also increase without much price increase.
Electricity isn't the only requirement for mining. Hardware is also required. Miners can't simply use lots of additional electricity if the hardware isn't there. Yes, new hardware can be manufactured, but it takes time.
The block reward decreases over time. If it's using Europe levels of electricity at time X, then after a block reward decrease, it'll use Europe/2 amount of electricity. This decreasing also disincentivizes manufacturing new hardware.
Miners can have different efficiencies, due to different types of hardware, and different types of electricity generation. So while the least efficient miner will be operating at near breakeven, the most efficient miner will be making much more profit. So while the least efficient miner will use $1M of electricity to mine a $1M coin, the most efficient miner will use less dollars of electricity.