Netscape basically died and was replaced by Firefox which doesn't/can't effectively charge users for the software so instead makes money by selling default search engine, etc.

Netscape existed as the internet was coming into existence. You used to have to buy a physical copy in the store to install it. People barely knew how to use their computers so the activation cost for bypassing their "pay wall" was high enough.

First, a self-correction: Netscape did not produce open source products until it open-sourced Navigator 5.0 in 1998. Until then, Navigator was freeware: free to download and run, but not open source.[1] I shouldn't have mentioned them, but my point still stands.

Second, it depends on what you define as success and failure. Netscape made its pre-IPO shareholders money if they timed their stock sales right. But the stock didn't go up because the company was profitable. It went up along with every other dot-com stock until the 2000-2002 crash, based on hopes and dreams, not fundamentals. The company never turned anywhere near close to a profit.

To me, a successful company is one that makes a sustainable profit based on its business fundamentals, not one that makes its founders and early investors rich in an investment bubble.

[1] Correction: Netscape did charge for the browser if used in a commercial context, but few people actually paid up.