This is an exaggeration, or you're not comparing apples to apples.

The used market for high performance PC gear is quite efficient. You're not going to get a high-end CPU or GPU from the past several years for pennies on the dollar.

Likewise, the resale market for Apple products doesn't guarantee 50% or more unless you're only looking at resale value of very new hardware. For example, you can pick up an M1 Max MacBook Pro (not that old) for closer to 1/3 of the original price.