I guess it depends on what the subject is, and how one defines success. As a product, Viaweb was a failure: it gained no market traction and Yahoo! didn't even use it for very long after buying it. PG and company might not consider the business a failure since it made them rich, but that's like saying cryptocurrency is a success because it made early Bitcoin investors rich. The jury's still very much out as to whether crypto will be a success among the other well-recognized successes in the business world such as telecom, oil, steel, and automobiles.
My understanding is Yahoo Stores was the Viaweb code base for a fair number of years. [1]
As a product, Firefox is still around. And Netscape disappeared in large part as an unsuccessful ground up rewrite as the brand continued following the company sale.
Bitcoin is not a company. Participants had different objectives. Those whose objective was to hold had success. Those whose objectives were political perhaps less so.
Entrepreneurs are in it to make money. Exits are how startups do it.
Telecom, oil, steel, and automobiles are state industries. Even if political correctness often demands pretending they are not…it wasn’t called the arsenal of democracy for nothing.
