1) Throughout most of high school, college, and years after college I smoked weed. I thought it was great, it made me feel good. I'd emphasise with posts on Reddit and such about how the "evil man was keeping us down", "it's just a plant man", "it's not harming anyone", etc. etc. Now that I'm older and I look back at that time, and man what a waste. I wasted so many years just getting high and accomplishing nothing. Yeah it didn't hurt anyone else. Yeah I felt good at the time. But looking back at my life do I get any satisfaction that during those years I felt good getting high and watching a movie and eating food, rather than actually moving forwards in my life? No, no I do not. It didn't get me anything other than fleeting good feelings, it's just being a drug addict. I haven't smoked in well over a decade now and I don't miss it for a second.
2) Along the same line, and counter to multiple other posters in this thread, I spent years on the whole atheist train. I thought people who believed in religion were just morons. I saved (cringe worthy) images about how it was superior to be atheist and various logical arguments for atheism, etc. Looking back on it, it's just another social hate cult. In that cult the enemy is the religious and they spend their time and effort just pouring out hate towards them. Just another hate echo chamber. It accomplishes nothing good. The older I get the more I see that traditional religion at least (for the most part) instilled good morals in people. It built solid communities. It accomplished good things. I'm old enough to have first hand memories of what communities used to be like, before the complete obliteration of religion in the west in the last 20-30 years, and I want it back. I'd rather be around those type of people than card carrying hate-based atheists. (Of course not all atheists are hate filled, but the people that make it part of their identity usually are.)