What's a shovel?
They're using the analogy of mining for gold. the cost of a shovel/pitchfork goes up when the price of gold goes down - which is a double whammy
you didn't answer the question. A shovel in this case is the equipment + energy needed to mine (GPU's etc.)
Which is pretty much obvious to anyone who has heard of bitcoin in the year of our lord 2026
Especially since the "sell shovels during a gold rush" has been used to apply to nVidia
But the person upstream hasn’t. It’s not obvious to them. Which is why a good answer has to include the detail.