Why is everyone spending time at Hackathons and not at Sellathons?

I've learned that 5 percent of a business is the idea, 15 percent is the product, and 80 percent is the selling. The number one reason companies fail is because they do not know how to sell? Isn't it better to spend more time at "Sellathons" learning how to sell - and less time at Hackathons?

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