Both is true in my opinion. Strange thing I witnessed, loyalty between corporations matter (e.g. suppliers and customers) and loyalty between people matters (just pick wisely, not everybody is worth it). Loyalty between corporations and people doesn't exist and is usually a one way street.
Yes, only be loyal to people who demonstrate some kind of altruism. I've had a client offer me a big raise on my hourly rate once without me even asking. It's a sign of trustworthiness.
