I can't support the claim myself, but I have seen a startup succeed as a professor's side project with his brother (lasted 10+ years, IPO).
Going all-in on your startup from day 1 might seem efficient, but it may not be most effective.
For instance, if I have an idea for an EduTech startup, I might e-mail some players/professors in the field and chat with them about the idea, and try to see why most startups in the field fail.
You have to wait until they respond, because your entire assumptions might fail! Keeping the youthful spirit is good, but talking to people who dedicate their lives to these fields is often invaluable. Don't build on top of unsteady assumptions.
"Launching fast" might not be the only way to test your assumptions.