I've had very bad things happen but I've known others go through similar things and turn out ok. I don't think you can compare yourself to others justly. No one really knows what another person's life has been like. Or, what it's like to be them.
All of this is just another way of punishing yourself. I don't tend to do that to myself. Obviously, I feel terrible for people who have had life much worse than I have but, it doesn't make me feel guilty for feeling as I do. It doesn't make me feel obliged to be grateful either.
I just think it's pretty monstrous that any of us got exposed to all this risk. So, I can feel sorry for them for the same reasons I feel sorry for me- we got landed with a mortal life full of these kinds of possibilities.
But sure- right at this moment, life isn't terrible and it isn't good. It's just treading water for me at the moment. I suppose there though- you need to decide. Do you want to make your life better than it is? In which case, you need to pursue how you might do that. That's definitely one thing I strongly believe in- everything in life takes effort. You don't complain about not winning the lottery if you didn't buy a ticket. 'Great' things in life don't just necessarily happen for people (unless they are extremely lucky.) More probable is that they saw something they wanted, pursued it and, were lucky enough to get it. Things like genes, health, wealth, circumstances are certainly a factor but, not always. Rags to riches stories exist too.