In many aspects of life, there are people that either add value or take value. Look at your social circle. There is likely the one guy you are hesitant to invite because he sucks energy out of social situations. Meanwhile, the guy who invited everyone out, and/or the life of the party, you value because he is adding value.
And that concept does carry over to investing. Some companies add value. Disney is the perfect example of this. Who doesn't love entertainment? And some companies suck value out of things. Look at the patent troll companies. What do they contribute? The companies that add value can keep adding value by just continuing to do what they do. Meanwhile, vulture companies have to keep finding smaller value producing companies to prey on.
I'm not trying to preach morality here, but long term investors should keep this in mind, as if what you do adds value, then you can keep doing what you're doing. But if all you do is exploit value, than there is considerably more risk in trying to keep that momentum going.