Then I thought about our burn, what the spreadsheets look like, how we estimate runway, and so on, and I realize this is uninformed madness.
If you believe this, then you understand that 400 people losing their jobs is the definition of the wholly controllable burn.
Heck, a 400 you should have a part-time or full-time CFO who manages much of that for you to avoid such situations.
It is hard to do at the best of times, particularly hard when things are tight to balance transparency with not wanting your team to start looking for new opportunities when things are getting close to the wire. Add to this different people have different perspectives on what is "close to the wire". For me it's 6 months, for many it's 12 months, for some it's less than 30 days.
The startup I work for does, and other startups provide this level of transparency as well. It's not hard, unless you're incompetent at communication and finance (but you shouldn't, right? because you're a founder/co-founder/leadership who has peoples' financial lives in your hands, because this isn't a game for people who need to make rent/mortgage payments every month).
"We have X in the bank, this is our runway, we have this many more months to be profitable or raise another round."