Cofounder relationships are among the most important in the entire company.
The thing that kills startups at some level, is the founders giving up.
If you compromise in the first five, ten hires it might kill the company.
What being a founder means, is signing up for this years long grind on execution - and you can't outsource this.
In general though, if you look at the track record of pivots, they don't become big companies.
Most things are not as risky as they seem.