If I had known then what I know now, I probably wouldn’t have been in a position then to need to know what I know now. Either I would have had the knowledge how to avoid that situation, or, because of that knowledge, I would have made different decisions earlier, which wouldn’t have led me to have to make the one I am now ruing.
Hindsight is tricky. Each decision we make brings us to where we are now. In terms of location, what we possess, who we know, and even what we know. Unweave just one decision (bad or good) and we would be going down a different path.
Example - “Had I known Amazon stock was going to be so lucrative, I would have bought stock in it when it first came out.”
Say someone came back in time and told you Amazon was going to be a “goldmine”. Now say you listened to them and bought stock. Does that mean you’d be a millionaire now? Maybe, maybe not. Having spent that money on stock meant you didn’t have it for something else. This month’s rent? Flowers for your girlfriend who you had pissed-off earlier? You may have stock in a fledgling company, but your decision to purchase it sent you down a different path. Perhaps on this path, your landlord kicked you out and you had to sell the stock at a lesser price in order to afford another place to live. Or perhaps your girlfriend dumped you instead of marrying you. Perhaps you hung on to the stock “at all costs”. What were those “costs”? Different friends? Different job? Different or no spouse? Each decision sent you down a different path. All because you knew then what you know now.