Leaving aside (if that's possible) the people are who are incapable of praising others unless the praise is somehow to their advantage, it really is a pleasure to praise others. A job well done is a job well done and ... well ... it feels good to notice and extol it.
Perhaps all praise does partake of some self-serving exaltation, but I wonder if there isn't some praise that doesn't seek any return on the investment. I'm really not sure.
And even if there is no such thing as praise without serving the self, is that always such a bad thing?
Certainly it's a pain to be in the company of someone who is constantly angling for praise or praising things mindlessly. And similarly it is a pain to be in the company of someone who can offer no praise -- the hoarders of secrets that will enrich the keeper of such secrets.
I guess praise is something everyone figures out for themselves.