But still, most of those things are one time costs: product development, failed products, fixing defects, certification. once you have completed those things, you can keep selling the successful product for decades right? especially now that the pace of innovation is slowing down. I mean just look at the clothing industry: a t-shirt today is the same as it was 10 or 50 years ago, right?

I would imagine things are super high tech and new, would need some iteration in their first 5 to 10 years, but after that, I don't know.

the costs that scale with each good sold is: Support, cost of returns, Sales, marketing, etc.