Just as a counter point I've got a cheap C720 I got 4 years ago for lightweight mucking about, and it has held up to daily use perfectly fine. I wiped ChromeOS and installed mainline Linux on it, which has great support for it. No problems with the keyboard, screen, power supply, or anything, and I've had to open it to remove the flash-protect screw, and it's survived several moves, travel and outdoor use.

I suppose I could be just lucky, but as is I could probably use it for another 4 years without trouble. The biggest issue is the soldered in RAM which is only 2GB. But that's plenty for emacs, light firefox, and even videos since it's got hardware decoding acceleration.