we are bombarded with a ton of information about what makes a good life/relationship/job etc, from parents, schools, religion, popular culture, politicians, friends etc, all contradictory. There really is very little way to sort the wheat from the chaff in all this advice without experience. neither you nor I woke up one morning and thought "hurrah I finally know what I'm going to do with my life!" and dreamed of this scenario and consiously made a series of choices to get us here.
Some people are lucky in that their formative environment furnishes them with the positive loving demonstration of the tools needed for a happy life. To them, the decisions I made must seem like madness.
My formative years furnished me with a work ethic, a love of learning, a respect for the opinions and differences of others, a love of animals, the ability to problem solve and think laterally, to see other people's point of view, the need to give everyone multiple second chances, and an understanding that I have to give until I bleed to hold a relationship together. My parents weren't trying to give me the latter 2, but it was the world view they were brought up in.
from that perspective, the decisions I made make perfect sense. We are lucky if we grow up in a situation that, in positive love, furnishes us with the tools needed for a mistake free happy life at an early age, but it is no more in our control than the financial, intellectual, racial or physical environment that we are born in to.
(Some people have early experiences that are so destructive that the shocking wrong-ness of their environment is recognisable at an early age: these people are not lucky, and it takes a lot of work for them to undo the damage)
The rest of us have fair to middling experiences that give us great tools and mindsets in some areas but wonky ones in others - it can take a lot of experience to work out which are the helpful tools and which aren't. SOme people have wonky tools but are lucky enough never to have to employ them (I doubt the queen can change a tyre or write a cv but i'm thinking she won't have to).
once we have the experience to show us which tools are working, we can make better decisions in future, and in hindsight we can see decisions where if we had done things differently, things may have turned out better (may, because we can't predict the future) but don't beat yourself up that luck didn't play you a different hand to work with.