I disagree on one point: I don't think startups are that much more risky than more "established" companies these days.
Established companies seem to fail or downsize reasonably frequently these days. The real question is if/when this happens, is it easier/harder to find the next opportunity if you've been a career "big enterprise" kind of person or have been working for startups?
You are right on the perception of risk, it doesn't matter if it's a startup or a bigco. The difference is you are working 60+ hours at a starup whereas you are working 20 hours of actual work if you are lucky at a bigco.
The 5-year failure rate of new businesses isn't the infamous 80 or 90 percent. It's about 55%. A big company job where there's a 45% chance that it will still be worth coming to work in 5 years would be considered very good.
Established companies seem to fail or downsize reasonably frequently these days. The real question is if/when this happens, is it easier/harder to find the next opportunity if you've been a career "big enterprise" kind of person or have been working for startups?