Do you have any particular reason for stating this? Having been in both environments, I actually think that academic grit translates outside of academia more fluidly than the other way around.

Conjectured reason: most academic projects have a horizon of 5-20 years to market and require large amounts of very mundane and uninspiring work. There are infinite distractions within academia. A successful academic project isn't going to make anyone rich, and even if it does, that person probably won't be you. Also, the pay is terrible.

Startup and even corporate life are very different in almost all of those dimensions. Projects succeed or fail fast. There are few distractions, especially for individual contributors. There's still routine work, but usually routine in the sure-to-succeed way rather than the sure-to-fail-and-be-repeated-10x-times way. A successful project can easily make you a valuable person -- either on the job market or in terms of actual net worth. And even if everything hits the fan, you're receiving a reasonable salary and building your career.

> It's also debatable whether a PhD absolutely implies an above average IQ

That is certainly true.