In my experience writing tech history, the most common reason is money. The second most common reason is entering a crowded market with little differentiation. The second reason could have been solved by marketing, but many in the industry are allergic to marketing.
If you are building a better <insert product here>, this must be heavily and clearly marketed. Otherwise, people have zero reason to switch. Why mess with what's working?
Additionally, just being cheaper doesn't make a product better. If I were starting a new effort, the cheaper part might be enough. If I already have stuff in production, cheaper isn't sufficient.
Feel free to tell me I'm wrong, but these are my observations.
I think you’re spot on — money and differentiation are the two cliffs most startups fall off.
A lot of founders underestimate how hard it is to get someone to switch to a new product. Unless you’re 10x better in a way that’s obvious, people stick with what already works. And as you said, being cheaper rarely moves the needle once something is in production.
The allergy to marketing is real too. Many teams think a good product will “speak for itself,” but in a crowded market, clarity and distribution matter just as much as the tech.
Your observations line up with what I’ve seen as well.