This happens every couple of years in tech. I've personally witnessed 3 downturns now. One was real and two were arguably the best time to start companies. Raising money might be harder, but generally only for bad companies.
Three? 2001-2002 was basically nuclear winter in my experience. 2008-2009 wasn't actually that bad except outside tech (although, I was in Iraq and Afghanistan during all of it). Before that, you'd have to go to early-1990s, when I was...12, and some HN readers weren't born.
I was thinking of 2001-2002 (genuine downturn) and then separately 2003-7 (great time to invest - e.g when I invested in Skype). Obviously 2008-ish (RIP good times) was the 3rd. Maybe I shouldn't have called them "downturns" but instead "depressed VC periods".
I was working in banking 2007-20010, and wasn't so wired into the startup scene then. What was good for startups and tech during that time? (Disclaimer - expecting a repeat of it in the next few years, want to be prepared).