ahhh.. ultimately, everyone is selfish to you...
sadly, with that kind of philosophy, a person becomes twisted and
bitter as the person becomes older (note i didn't use the word
"grows" older)
i guess the long and short of it is.. sometimes there are no
ulterior motives...
stop looking for them 
after this exchange with you, i start to understand why a lot of
people especially at work view me with suspicion.. and some,
downright hostility..
i never had, and will never have ulterior motives for what i say
and do at work.. and they seek to find these motives... and they
fail to find them where there are none...
the lack of such motives make them feel uneasy... they think that i
have somehow plotted it in such a way that they are unable to see..
and then start to suspect me...
i brushed that aside when i was told this by a friend and
colleague... one of those good friends made at work... i guess he
was right..