Totally!! Especially if you are maybe unhappy in work, bullied/unfairly treated, overworked - feel misled that the degree you were told was the be-all and end-all didn't end up being all that - and you get to a stage of your life where you are looking at 'regrets', missed chances, wrong decisions, etc etc.... That's all pretty normal!!
I'm envious of others who have been in a position to retire early, but I don't begrudge them either. It's only human nature to reflect on how different decisions taken in the past could have led you down another path. When you look back, so many things that have happened in your life did so on the literal turn of a coin, a decision that didn't feel that big a deal at the time, but had a huge influence on your life going forward.
That's the 'glass half empty' though. There's always been the good stuff - the children you might not have had, the friends you might not have met, the experiences you could have missed out on. It's not easy but all we can do is to focus on them.
I know, for me, I have had so much of micromanaging and a toxic work culture - it's totally fucking with my mental health and I just want out. I can't afford to just throw in the towel, but for me, I am looking at options.
Life isn't fair, not one bit, but for most of us, it could have been worse. Hang in there.