It's hard to be an expert when you're talking to experts. But clearly Mike Gettis and his business partner Aasish Nathwani knew what they were talking about when they pitched Endy to the Dragons.
Not only did the pair discuss impressive sales numbers, but they engaged the Dragons by having them experience the mattress. Not just trying the mattress, but unboxing it, setting it up, and laying on it.
This was characteristic of a "showrunner" style pitch (from: "How to Pitch a Brilliant Idea" by Kimberly D. Elsbach). The partners engaged the Dragons in a transparent way and demonstrated technical knowledge and success.
Endy went on to be a massive success. When Mike and Aasish pitched the company, they asked for a $20 million valuation. They only got $13 million. A couple years later, the company sold for $89 million. For some reason, the Dragons weren't as eager to buy the idea as might have been expected.
Why?
The partners' weakness was hesitancy. They didn't show the excitement they needed to. Clearly, they believed in their product. And it was obvious the product was already a success. But they didn't display their own enthusiasm, which resulted in a muted response from the Dragons.
The deal still went through, but with perhaps some excitement, they could have achieved the deal they had originally asked. It's not enough to be an expert. You have to be excited, too.
Extended version: https://www.cbc.ca/dragonsden/pitches/endy-sleep