I have achieved these results around 2015, sitting at home, relaxed. I was not in a match situation observed by millions. Such a situation can knowingly lead to blunders like Kramniks overlook of mate in 2.
I also sometimes "cheated" by aborting the game when I was tired and continuing it the next day (if at all). That's what the player in a match can not do.
I also sometimes restarted a game at a specific position. Can also not be done in a match. Finally, they used better hardware in these matches. I had eight threads on my old Laptop and I used four of them. The Laptop itself was bought around 2005. Between 2000 and approximately 2020 I trained every day and I was on my peak. I am still around 2400 on Lichess today, without training.
So, I hope it does not sound that extraordinary any more. It isn't. Maybe it is now, but not then.
2015 stockfish is quite a different beast from 2026 stockfish. Stockfish didn't even add NNUE until 2020.
Based on what data I can find, it's estimated that the difference between the 2025 stockfish (stockfish 6) and today's stockfish (stockfish 18) is nearly 400 points.
That's the difference between Magnus Carlson at his peak and someone who doesn't even have enough rating to qualify for the grandmaster title.
So yes, the fact that you beat stockfish in 2015 doesn't sound extraordinary, because AI today is vastly stronger than it was when you achieved those results. What sounds extraordinary to people is your belief that you could repeat those results against today's top chess engines.
Out of sheer curiosity, I did a bunch of research to understand just how dramatic a 350 point rating gap is in real word chess. Magnus Carlson, for example, has a 98% win rate against players >350 rating points lower than his own, with zero recorded losses.
In fact, there is only one game I could find in all of Chess history (Anand vs Touzane, 2001) where a super GM (rating >2700) dropped a classical game to someone more than 350 points below theirs (gap: 402 points). (it's estimated that there are between 2000 and 3000 classical games in history played between Super GMs and players >350 points below them) And it could easily be that Anand was ill, or suffering some other human condition which made his play significantly worse than his typical play for that game - which you would not see from a computer engine.
In other words, the Stockfish that you beat in 2015 would itself be expected to get 3-5 points (that is, 6-10 draws and 0 wins) in 500 matches against the best chess engine of today. The delta in strength is immense, and it is reasonable for everyone else in this comment thread to assert that you would have zero chance at all of picking up a draw against Stockfish 18 in a fair game of any time control, regardless of how many matches you played.
I have achieved these results around 2015, sitting at home, relaxed. I was not in a match situation observed by millions. Such a situation can knowingly lead to blunders like Kramniks overlook of mate in 2.
I also sometimes "cheated" by aborting the game when I was tired and continuing it the next day (if at all). That's what the player in a match can not do.
I also sometimes restarted a game at a specific position. Can also not be done in a match. Finally, they used better hardware in these matches. I had eight threads on my old Laptop and I used four of them. The Laptop itself was bought around 2005. Between 2000 and approximately 2020 I trained every day and I was on my peak. I am still around 2400 on Lichess today, without training.
So, I hope it does not sound that extraordinary any more. It isn't. Maybe it is now, but not then.