I make a point of introducing myself to people online who are unlikely to become clients. You for instance.
That's not altruism. It's curiosity. Learning about other people's business models, industries, unique challenges and goals -- even absorbing their phrases, vocabulary, and style -- prepares me for some other branding client later on.
Being attuned to other people is the starting point of real life interactions, isn't it? Business networking is no different from wandering around from the car mechanic's to the coffee shop and striking up conversations with people along the way.