Two core groups of people are well-suited to be economists:
1. You math GRE score is over 800, you are totally focused, you love working long hours on your own, and you have good enough letters of recommendation...
2. You could be happy as an academic without much of a research career. Working at a teaching school is a rewarding life, albeit a poor one relative to your investment in human capital.
I would say that #1 is only a necessary, not a sufficient condition, to head in the direction of becoming an academic star. I would say that #2 should come with the caveat that many of the small colleges that value teaching are in small towns, which puts limits on spousal career opportunities and may otherwise constrain your lifestyle. Also, the caliber of students at small colleges may be declining, for a variety of reasons.
I see academics as very much a status game. You worry about whether or not you have tenure, the reputation of your department, the reputation of the journals in which you publish, and so on. I would rather play a game where I can gauge my impact on people's lives than one where position on the pecking order is everything.
A non-academic might have major investments in a family, friends who are not colleagues, hobbies, and voluntary organizations. Academics instead tend to have very concentrated emotional portfolios.
When you choose a career, it is important to consider the people with whom you will be spending time. Those suited to academia may be invigorated by the cocktail party chatter and lunchtime banter of professors, and they have a hard time engaging with ordinary people. I am more the opposite.
Another way to look at economics graduate school is, "Compared to what?" I think that compared to a Ph.D in philosophy, an economics degree is likely to give you better opportunities. But my guess is that the right sort of engineering or biology degree would create even better career choices. I think that law is likely to be more career-broadening also, if for no other reason than it puts you into contact with practicing lawyers.
If you are attracted to econ as an undergraduate because it combines math and philosophy, be aware that in graduate school the philosophical part pretty much disappears. In that sense, economics at a graduate school level is not as far removed from engineering as you might think.