Size of "sympathy groups"

"...Make a list of all the people you know whose death would leave you truly devastated. Chances are you will come up with around 12 names. That, at least, is the average answer most people give to that question. Those names make up what psychologists call our sympathy group. Why aren't groups any larger? Partly it's a question of time. ...To be someone's friend requires a minimum investment of time. More than that, though, it takes emotional energy. Caring about someone deeply is exhausting. At a certain point, at somewhere between 10 to 15 people, we begin to overload." -The Tipping Point by Malcolm Gladwell

I wonder whether if we learn to accept death, we'd have enough emotional energy left to love more people. Thoughts?