I can't count the number of times a client has sat across from me, bravely recounting details of a difficult experience, and ending with some version of "it's fine" or "but that was along time ago" or "you know, so many others have had worse experiences".
Here's the deal, you can always find someone with a "worse" story. That doesn't diminish your experience.
When we go through hard stuff, it's hard for us, period. If you fall off a 20 foot cliff, that's gonna leave a mark, if you even survive it. If the next day you read a story about someone who fell of a 30 foot cliff, does that mean you're not hurt anymore? Does it mean your bones are not broken, your wounds are suddenly healed? Of course not, so why would psychological trauma be any different?
So why do we hold to this idea?
I believe this comes back to the root of our Puritanical culture that tells us not to complain. The idea that no one really wants to hear about your struggles, and when bad things happen you should just suck it up and carry on quietly. If you're unable to do that then you're either weak or needy, and probably both.
One of the results of this thinking is that it keeps us from gaining ownership of our experience. How events affected us, and how that shows up now is crucial information for us to pay attention to. If we dismiss this information, it makes it very difficult to "deal with it". Which in my mind means we have fully incorporated the experience, that it no longer causes us unexpected intense emotions, and it does not prevent us from doing the things we want or need to do.
How can we get there if we keep denying to ourselves that the event was a big deal for us? Our stuff is our stuff, if it keeps popping up, causing us discomfort (sadness, anger, anxiety, fear) then it's a big deal (to us!) and needs attention. Acknowledging that, and validating your experience, without comparison to events that happened to other people, can go a long way towards starting to heal from it.