I guess that Sun were just too nice a company to prosper
Well that and they were way over priced ...
Well that and the Open Source Community caught up with them ...
Well that and they didn't have a long-term solution/strategy to ensure new entries into the tech field could gain experience/skills on their products so they would be comfortable recommending them. Sun relied on the old guard to recommend Sun, while newer entries onto the computer field were more comfortable recommending solutions they had experience with.
As a result apache replaced Sun's web server as the standard.
Red Hat (and others) took away Solaris server market share.
New startups began by running Oracle and other databases on Linux (or even Windows) servers in the initial low funding development stages and then when it came time to go into production, some of them didn't bother with moving to Sun hardware and Solaris, and instead remained with what worked and building it out to be "good-enough" for less money and less headaches.
I was in college from 1995-1999. The guys who loved going to the lab became Solaris die-hards, because that was what the school at that time ran (it is now LINUX, LINUX and more LINUX). But I preferred working in my apartment, so when I had took C, LISP, and JAVA classes that were focused on the fundamentals of code, things like recursion or objects, my teachers didn't demand I used the Solaris workstation, just that I solved the problem and got a strong foundation. So I installed Red hat on a backup PC and worked by using the same languages, with the same libraries, with the same text editors only on LINUX as the labs used on Solaris. At the time, I was the minority, but with each new class the LINUX users increased and those willing to invest in learning Solaris decreased, not to mention a larger and larger percentage of Solaris guys knew both.
When I went to work for a startup in California, they couldn't afford the quotes for Sun, so I purchased three DELL servers and installed Linux on them to accomplish the same task. Now nobody asks for Solaris admins, they ask for Linux admins.