Yeah it's better not to get a extended warranty on anything, unless you are 90% sure that something is going to happen to it. If something is really not alright then there is no point of getting it in the first place and getting a warranty over that. I would rather get a PC for 700$ instead, since that might (not always of course) be more stable and last longer than getting a 400$ PC and adding 300$ extended warranty.

Usually technology things etc. are not meant to be lifelong and when you are buying a 400$ computer in the first place you are taking a risk, so the extra 300$ shouldn't help a lot, chances are that something might happen to the computer right after the warranty period... so you never know.

Usually people think that if you get an extended warranty it is going to help you if your product gets ruined, but this is not always the case. Chances are that nothing is ever going to happen to your product. So in my opinion most of the times an extended warranty isn't necessary, but sometimes they are helpful (if something is really expensive) , which solely depends on one's luck.