

Laptop performance when closed is quite variable, but depending on where you live, each 10W of idle consumption 24/7/365 could cost you somewhere around $20/yr (assumes @$0.20/kWh, YMMV). This isn’t overwhelming on it’s own, but it is “cost difference between a junked laptop and a Raspberry Pi” kinda money.
I think SD card failure rates are way overblown if you’re buying from reputable manufacturers (Sandisk, Samsung). I’m sure they do occasionally fail, but I’ve never experienced one.
You’re right, for really intensive tasks the costs can climb, but I see people asking for ideas for what to do with a junk laptop and the top suggestion is always something like pi-hole or a bookmark manager that could run on a potato.
Like with most things in life, it depends.