> Has anyone ever typed so much on a keyboard that the switches wore out? Aren't they good for literally millions of actuations?

Yeah. Several. The keyboard might claim it's good for millions of actuations, but I write as well as program. At the end of the editing process, I have roughly 80,000 words entering the public sphere, a month. Excluding all rewriting. Imagine the abuse the spacebar has seen by the end of that.

It doesn't take much to scale that out to be murderous on cheaper keyboards, and serious wear and tear on the tougher ones.