It's said that intelligent people have fewer friends, but they tend to cherish the friendships they have more. I suppose intelligent people will also more critically distinguish between friends and acquaintances. A lot of people seem to get those two things confused.

To be able to walk away from a destructive friendship, is also a useful quality to have. Friendships where the other person is just living of your positive energy, draining you, so to speak, should be a warning bell to walk away.