I'm surprised to see such a bad take on resource allocation on HN.

When provisioning servers, do you average your throughput and get enough capacity for that average?

Of course not, that would be assinine. You need to be able to serve 24 hours a day, even - especially - during your edge cases. Follow your advice and explain to the CEO that since Black Friday is a "low frequency event," it's fine that your site was down during that one day.

A better argument is that you should choose things, including houses and cars, based on edge cases since that is where meaningful differentiation occurs. If I take one road trip each quarter and my car is unable to handle it, then I bought the wrong car.