Had forgotten when I hit that milestone, but remember being pretty damn happy about it -- though I'm talking about $100K of 401k assets, not net worth.* I checked back and found that it was at the end of 2005, after 8 years of working (with a regularly increasing salary and concomitantly increasing 401k contributions).
Now, 8 years later, that account is over $400K. On pace, with a 5% return and present contribution+matching+future catch-up contributions, for @$800K in the next 7 years (yes, barring any major meltdowns). But of course, I'm secretly hoping for 7%, so I can break the $1M mark! Yeah, like a lot of people, I'm enthralled with the idea of having "a million in the bank," so to speak (even though I should reach FIRE at well below that).
Lord how I wish I'd stashed some money in an IRA when I was 20 and in the military (rather than, quite literally, "spending like a sailor")! As one retirement seminar instructor put it recently, "I'm increasingly convinced that the most powerful force in the financial universe is an enlightened 20 year-old." Amen to that.
* net worth between the wife and I now @ half a mil.