Well, because the fact is the bad things generally are true and those who accept them know it, while good things can often be said out of pity.
Accepting truth is a bitter pill to swallow and we as humans strive to be good people, which includes the accepting of bad news rather than the denial of it because of a good person's honesty policy.

Now here's the good news, we control the choices we make in life, there is some semblance of legitimate redemption for those who make a conscious decision to make good life decisions if you ask me.
Always try to lean toward making good and smart life decisions and you'll find that there are less negative things to accept.