Heh. I misremembered the date--thought it was today, but looks like it was October 5. On that day, 10 years ago, I posted a link to Mastodon on Hacker News, with the title "Show HN: A new decentralized microblogging platform". That it made it to the front page ended up bringing the first 5,000 users, setting the project on the trajectory it's on today.
At that point I was 23, freshly graduated from university with a B.Sc. in Informatics, living with my parents, and freelancing on the side (I had a freelancing career in web design since high school and went to university just to get a degree). I was able to save a lot from my student loan as well, so I had the opportunity to experiment with this open-source side project.