Your knowledge of computers should be supplemented by knowledge of economics. While it is true that power consumption could grow unbounded, it is also true that this should only happen as long as it is economically feasible to do so. Granted there can be a speculative element to this, but what it comes down to is an equation similar to the following must hold: Cost of power < (value of bitcoin + speculation of increase in value over an acceptable time horizon)*acceptable risk weighting I'm sure someone could come up with a more accurate and elaborate equation, but that's the gist of it. As such, there is a practical limit to the power consumption of bitcoin, however this limit is not fixed. It will change with respect to those dependent variables and of course and everyone investing in mining will have different time horizons, risk tolerances, and expectations of appreciation. Having said all of that, you should compare this to the power consumption of the traditional banking system. This should include the power consumption of all banks, companies related to credit cards and processing systems, etc. I don't know how much that is because I've not looked in to it. Finally, the traditional financial systems consume most of their power across data centers and retail locations globally. In these places, these power costs are further increased by increased requirements for cooling capacity. As mining matures, it would make sense for miners to locate their mining operations in places where cooling is relatively cheap (or free). These mining operations could even be housed in apartment buildings in cold climates and integrated in to heating systems such that the power consumed by mining is offsetting heating. I'm not suggesting any of this kind of thing will happen or that it's likely, but to premise your entire statement that bitcoin in specific can't thrive due to infinite power requirements shows a complete misunderstanding of economics with respect to offsetting and the simple fact that people won't add more mining power (and thus spend more on electricity) if the value of bitcoin doesn't rise. In fact, the actual mining capacity is capped by electricity costs with respect to bitcoin's perceived value. You also completely disregard any concept of a crypto currency that does not rely on "wasting" cpu cycles.
I don’t think that going to the gym is a waste of time, there we can do the exercises more professionally with a trainer or take an example from others.