As a kid, I always had an interest in them. I'd play my brother's copy of Soul Calibur 2 all the time, just going through Weapon Master cuz I had no friends. Later on, my love for SMT brought me back into fighting games when P4A dropped. Once again, I played by myself, and occasionally also with randos online (with shitty ps3 wifi, sorry!), but I was never actually learning the game - just pressing buttons. At some point, I watched the Best Friends Play 3rd Strike video on Machinima, and just thought "wow, that artstyle is great!" This becomes relevant in around 6-7 years.
Years later, when DBFZ first released, Woolie on the Super Best Friend Cast told everyone listening that if they wanted to get into fighting games, they should play DBFZ. That stuck in the back of my mind for a bit, but I couldn't afford a $60 game at the time. Then, Voksi released his crack of DBFZ, including the entire first season of characters and an online patch. Everything lined up too well, so I grabbed the torrent and booted it up. For once, my main focus was playing against other people, and actually caring if I lost. I'd look up YouTube videos for my mains, videos on team compositions, videos explaining frame data (had to watch a bunch of those before I got it lol), everything. I was in hard, and I never left.
Eventually, I found Fightcade. Fightcade 1. The Fightcade where every time you looked in the chat, there was some Mein Kampf shit going on. I stayed for one reason: 3rd Strike. 3rd Strike is where I really went from a child to an adult in terms of fighting games, and it's the game I've put the most hours into. Also, it showed me what good netcode could look like. I'm incredibly grateful for that platform and everything it's done for the retro fighting game scene.
TL;DR, DBFZ taught me basics, 3rd strike cultivated me long term.