"less than 1%"Are you thinking VC-backed startups, or maybe lumping them in to your calculation?
Remember, we're talking bootstrapped businesses designed for profitability. I think you'd be hard pressed to make ten real efforts in a row, learning lessons as you go, without getting one of them to stick.
For VC's, where "profitable and growing linearly" equates to failure, then sure, the odds are worse. But that's just another reason not to go that route.
tens of thousands of dollars
For what it's worth, the 4 big multi-year failures I reference above cost maybe a few thousand dollars total over the span of 10 years, and happened primarily in spare nights & weekends during the course of an otherwise active and non-ruined life. Most people who met me never knew it was happening at all, and no friday beers were missed as a result of the aforementioned bootstrapping.