I've bought it before on a car that gave me trouble all the time. I was slightly short of making that money up with that kind of car. I told myself I would never fall for that again. I've also worked in industries 10+ years ago regarding various warranties. So many companies have done statistical analysis on the profits of these are they are astronomical. Why do you think that you get letters in the mail asking/recommending to renew your warranty? Because there is strong statistical showings that (and I'm just making up numbers here just to prove the point since I don't know what the figures at Nissan are), for example if the extended warranty is $2500 and they average out to $750. I say $750 in this case because the standard is some where in the ball park of 30% or less...meaning when they sell you this they are making 70% pure profit. It's a HUGE gain...more than selling a car, more than selling any kind of product, etc. That's why it's so big and such a big push for it. The slogan in that world is you've just sold somebody paper for 70% profit. Been there on both sides. I don't do it anymore because I know that statistics behind that and I've always been about probability.
Now I have a car that statistically is one of the most reliable. IMO, I'd be nuts to take that bet. In life, it's all about taking your chances at the right times.
Plus, when I bought the car the Infiniti dealership sold it to me with an Infiniti certified warranty that is 100k miles, but that only covers engine, trans, etc. They basically said I would be covered 100% for everything similar to a base FX...so like nav, tech, etc would not be covered. If I bought this, it's almost like that didn't even matter at all, but it does.
Plus the other thing you have to be conceded with is stuff that doesn't get covered anymore because of mods. Sometimes I wait until out of warranty to start doing mods like remote start, alarm, exhaust, etc because then at that point it's yours no matter what....if someone screws up an electronic install even under an extended warranty you'd still be screwed in general.