Is Apache the Most Important Open Source Project?
Back in the mists of time - I'm talking about 2000 here - when free software was still viewed by many as a rather exotic idea, I published a book detailing its history up to that point. Naturally, I wrote about Apache (the Web server, not the foundation) there, since even in those early days it was already the sectoral leader.
In the 13 or so years since I wrote that, Apache has managed to hold on to its commanding lead over Microsoft, despite two massive - and doubtless massively expensive - campaigns by the latter to dethrone it, as evidenced on Netcraft's graphs by market share surges to nearly 40% a couple of times during that period. But once those campaigns were over, Microsoft fell back to the baseline 20% it retains today.
That shows something really important that goes beyond merely succeeding, which was why I wrote about Apache all those years ago.