I think LUCK trumps the HARD WORK in any path of life.
I never believed in luck that much. So I worked so hard for many years. But now, seeing how others are doing, I think LUCK is the game changer compared to HARD WORK.
HARD WORK is necessary in terms of survival. Say, you join a company just play farmville on FB without doing assigned work, of course boss will kick you out next month. But working hard doesn't mean you will level up in the career or getting a massive bonus at the end of the year.
And same is true for romantic stuff. I see some kids in here getting hooked up in their first week here, for the rest of their lives. Some try hard and get one in a later year. Some.. they never make it despite how much effort they put in (like the idiot writing this

). Some even meet their life partner at unlikely places... like gym (I am serious.. my best of bestest friend met her husband at a gym!)
As for my friend at Harvard, I think his case was more towards LUCK. I think he had some relatives who were studying in US. So he did have the right info to begin with in terms of going for studies there (something I never had). Then he entered PhD just to extend his stay in US, so he can become a naturalized citizen. I am pretty sure he was working under a right professor, otherwise he won't be hearing such job openings (i.e. Harvard). Obviously, he has played a part too.. mainly assimilating with the local culture. I heard some SLs in US never even tried a hamburger or pizza. In that context, my friend has made a quite a progress. I am so happy for my friend. At least he is living the dream what most of us dying to achieve.
Having this understanding, I don't dare to bet too much on things that require enormous quantities of LUCK.