Does it make sense to fix up an old laptop?

For what it is worth.

"Instructables" says this:

Why would you want to do this? Well computers really have not gotten that much better(at least CPU wise) in the last decade so old laptops can be surprisingly useful. Also sometimes you just need a really cheap laptop. Or one that you don’t have to worry about getting broken or stolen. Plus it's good for the Earth to get the maximum use out of a thing before discarding it. 

https://www.instructables.com/id/Fix-Up-an-Old-Laptop/?utm_source=newsletter&utm_medium=email

For me, the old laptops are now purely used for the sole purpose of having a local backup of things. Other than that - they have a very limited use (for software testing).