I learned about bitcoin through a random advertisement while playing online games. It says something about earning free money, after that, I searched about cryptocurrency and tried different faucets where I earned a decent amount of satoshi. I learned about it way back in 2013 however, I became interested in it when I joined this forum. I wish I could've invested more money when I first knew about bitcoin, the price of BTC during that time is just around $500.
I don't remember exactly when or where I encountered bitcoin, I also earned bitcoins through faucets and bitcoin bonus games. In 2012 and 2013, when the price of bitcoin was not too high, joining the faucets, we received a lot of bitcoin, not less like today.
Not only you, I believe many people regret like you for not investing much in bitcoin at the time. However, I think few people believed fully in bitcoin at that time since the future of bitcoin was uncertain and we regret seeing the development of bitcoin today. If given the opportunity to go back to the past and forget about the present, I believe we would never have invested in bitcoin at that time.
I first heard bitcoin from my uncle way back 2015 but I wasn't interested at that time because it was still too gibberish for me and I'm too indulged to do earthly things at the heigh of my teenager life. Only got interested last 2017 and that's was the start of my bitcoin career, if only we could get back at those times.
But I do agree, even if we had the same opportunity and had the chance to go back time, we still have the same response and won't still give bitcoin a chance to prove itself because I believe 2015 was the height of scams and pyramid schemes, so I don't really blame people if they look at the bitcoin as one of said scams/schemes.