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.