Increasing usage trivially and obviously increases capacity by ~the same amount. A toddler could understand this, because obviously the lights are still on. We use more and more energy every year (except 2020, for obvious reasons). There aren't rolling blackouts. Thus, capacity responds to usage.
I don't know why you're reaching for the word "magically". There's nothing magical about the mechanism of how this happens. Its just market dynamics. If explaining it by calling it "magic" helps you understand it better, though, then that's fine.
> Increasing usage trivially and obviously increases capacity by ~the same amount. A toddler could understand this, because obviously the lights are still on.
It may increase capacity over time, if someone thinks they can profit from bringing new supply online. This is known as supply elasticity, and it’s pretty well-studied. It’s not trivial, and it’s not instant. In the meantime, demand from crypto may also reduce demand from other consumers, who now have to pay more for electricity. Electric usage is more nuanced than “are the lights on or off”—families can and do decide to keep the house colder in the winter if prices are up because some people decided to waste a bunch of electricity on crypto in a data center somewhere.
You’re missing the point, though: the thing that absolutely does not happen when you increase demand for a resource is that resource becoming cheaper, unless that demand goes away later, after the supply has increased. This is a called supply glut—also pretty well-studied.
Now, given that the entire cryptocurrency sector is a con and will eventually vanish like a turd down a toilet, there may very well be a period later on where the result of all this nonsense is that we have lower electricity prices for a while. Until that happens, though, you aren’t making electricity cheaper by using more of it.
I don't know why you're reaching for the word "magically". There's nothing magical about the mechanism of how this happens. Its just market dynamics. If explaining it by calling it "magic" helps you understand it better, though, then that's fine.