I've had Macs since the original version in 1984. Maybe close to 20 in all and I had only one fail me by having to replace the motherboard for about $300. In all my Macs I had one hard drive failure. Currently I have a MacBook Pro retina display, a MacBook Air and two older still working but essentially retired MacBook Pros dating back 7 and more than 10 years I think. They were progressively replaced simply because I wanted something faster and better or compatible with the current OS.
I still have my original first 100 day Mac with the signatures inside the case. It operated when I last used it but it now has been several years since.