רבי אליעזר הקפר אומר, הקנאה והתאווה והכבוד, מוציאין את האדם מן העולם.
Jealosy, lust, and honor take a person out of the world. (Avos, 4:21)At first glance, this mishna seems so straightforward that there shouldn't even be a Rashi on it; what, after all, is not self-evident about this mishna. In fact, it almost seems like I don't need this mishna at all. On second look, however, one has to wonder.... Taking a person out out the world (in fact, both this world and the coming world) is very strong wording about three things that aren't even actually issurim! There are lots of things that I would have said are worse. Rashi actually deals with this mishna in three ways.
First, Rashi just deals with why these three stick out. On kina (jealousy), we have a pasuk in Mishlei 14:30: "jealousy rots bones". For ta'ava (lust), we have a pasuk from Koheles 5:9: one who loves money is never satisfied with money. The problem being that the ta'ava can never be fulfilled, so it becomes all consuming. Rashi indicates that love of money is just an example ta'ava, but the same can be said about going after ones desires in general. If the desire is leading the way, it can never be satisfied. Finally, on kavod (honor/glory) we have a ma'amar Chazal, "positions of authority bury their officers" (Pesachim 87b).
Rashi, in his second explanation, deals with the phrase "es haAdam"; and understands it to mean that these three midos were the root cause of Adam haRishon losing Gan Eiden. The jealousy and glory was from the the malachei hashareis who gave Adam haRishon great honor by roasting meat and preparing wine for him, and then in turn were jealous that he commanded such kavod. The ta'ava was Adam's desire for the eitz ha'da'as tov v'ra. Combined, they forced Adam's expulsion from Gan Eiden. (Rashi gives no further explanation, but one may speculate that that the kina and kavod shown to Adam distorted his judgement and then the ta'ava was the knock out punch.)
Finally, Rashi puts these two explanations together and looks through history for examples of people losing both worlds (haze v'haba) and traces their root cause to one of these three midos. Korach was jealous of Moshe, Geichazi (Elisha's servant) lusted after Na'aman money, and Yeravam ben Navat could not tolerate the kavod of Beis Dovid.
It may be that Rashi's last explanation is designed to show how these very powerful midos, which were instrumental in removing Adam haRishon from Gan Eiden, continue to be a the root source of continuing misery. Forewarned is forearmed.