I don't think it's about the bad stuff, per se, so much as it is about the effects the bad stuff had on you. If you're happy, have fulfilling relationships, don't obsess about things, have a positive self-image and a good sense of your own self-worth, then you may not need to be in therapy. Some people (I think a small minority) can get through some really bad stuff without long-term negative consequences.

I couldn't. The bad stuff that happened to me in my youth has affected me all my life and left me distrustful, scared, somewhat self-loathing, and, most importantly for me, alone. I don't like any of those things, so I'm in therapy develop more beneficial coping mechanisms.

As to whether everyone had bad stuff, it depends on how you define bad stuff. I describe stuff my grandmother did like it was no big deal and T says "you know how crazy that sounds to someone who didn't ever see that before?" I described how my parents used physical force for discipline and shrugged it off with "everyone got hit as a kid, right?" and he said "no, not every child was hit by their parents."

Sometimes it takes an objective eye to help you figure out what's "normal" and what isn't and the effect the stuff had on you.