Because you don't know who you are talking to. Is this person -
whom you plan to confide in - going to hear and/ guide you? Is he
or her a trustworthy person? And is it done in a timely fashion
where he or she is ready to listen?
Secondly, the stigma. Nowadays, you are automatically considered
"a problem" if you voice out what's been keeping you down. I
understand that most people are living life on a hectic pace and
the last thing they want is to be bogged down by someone who,
inadvertently transfers his worries onto you. It's tiring, it can
be off-putting at certain points to hear someone out when you
yourself are preoccupied with your own things and/ don't have a
marathon-of-an-energy and patience to deal with such complex issues
that involve emotions.
I personally let it "slide" when I don't want to confide my
personal thoughts with anyone (when the time isn't ripe).
That's right. one should always solve own problems, don't burden
others