A lot of things in life suck. Not everything sucks the same amount, though. If all of your friends want to hang out with you on the same night, but it is the one night you want to relax by yourself, that may suck, but not nearly as bad as getting stuck in traffic when you're in a rush. If you get stuck in traffic when you're in a rush, its level of suck pales in comparison to getting your leg amputated.
There are quantifiable levels of suck. Some things are minor inconveniences; they only suck because things did not go exactly how you planned or desired, but by the next day you will have forgotten about it. Some things are major inconveniences: your car breaking down, getting into a crash with another person, or losing your job (or, god help you, all three); they can take considerable amounts of time or money (or both).
Some things are more than inconvenient. When somebody is gone forever, that sucks much more. You don't wake up the next month and forget about it; you don't wake up three months later and forget about it, either.
Getting your leg amputated is a thoroughly life-changing event. You may get a prosthetic replacement, and it could even be better than your old one, but you will never have the legs you were born with again. Your very being is permanently changed. No matter what kind of positive spin you put on it, or how long you live with and grow to accept it, losing your leg sucks. And it sucks a lot more than somebody screwing up your order at a restaurant.
Stories are pretty much about things that happen that suck. Stories where nothing sucky happens are uninteresting. But the level of suck that a story deals with is very variable. The higher levels are more serious business. How serious do you want your story to be?