33% is way too low as a failure rate for pre-seed startups. I think that number may be around what you would expect for Series A startups. The data is skewed because class sizes have grown over time so the data is skewed towards younger companies.
Another factor is that it takes some time for a company to admit it failed, and everyone's opinion of "failed" is different. I suspect the actual number is higher, especially from an investors perspective.
If you can just avoid dying, you get rich. That sounds like a joke, but it's actually a pretty good description of what happens in a typical startup.