Almost every time I've broken something, it's because I pushed it too far. I generally don't kill stuff foolhardily, but I know the limits. Two motherboards burnt up at the ATX connector because the PSU couldn't supply ample power to the 5v lines. Did I fix it? Yes. Would I have gotten an RMA? Probably, probably not.
I think it's OK to RMA to a manufacturer if you tell them that you broke it, and it's your fault. Then they can decide whether or whether not to give you a second chance with a warning or to refuse. I know this because I've heard the techs from one particular company, Epox, talk - their stance is that if you tell them you broke the product, they will honor the RMA, but if you lie and they find out it was most likely your fault, they won't.
That's honesty, and there's nothing wrong with that.
RMAing because you got an early stepping, however, IMHO is not right. Returning it and paying a restocking fee is an abuse of the whole return-a-product system. It is there for those who wanted a vid card and accidentally ordered a CPU, for those who wanted a 1600+ and got a 1.4GHz Tbird. Most of the stuff that I've owned hasn't been very overclockable - the AGOGA 1800+ palomino, A1-cored 9700 Pro, 1300 SL5ZJ Tualatin, and so on. They were all early steppings. They all clocked like crap. Did I return them? NO! I got what was advertised.
Oh.. about the age thing. I think that people who break stuff and have little cash on hand tend to be the ones RMAing for not-so-good reasons. Younger folks tend to have less money, and tend to be more mischevious in that regard. Note the word tend. There are people who never grow up, and there are people who know the right path in their preteens. There are young people who are rich and old people who are broke and need to leech all they can.
My dad thinks that most computer hardware enthusiasts are in the age of 17-20. Go figure.