That&#x27;s getting close to a &quot;no true Scottsman argument.&quot; You go through the list, find every successful open source project, and try to explain why it doesn&#x27;t count.<p>Some of your examples are flat out wrong: Oracle was the big dominant proprietary player when Yahoo decided to risk going with MySQL (which was great, and I can&#x27;t wait for MySQL to get replaced by Postgres).<p>Now think how many websites are running on WordPress. It pains me to say it (because the code quality is so bad), but that&#x27;s an example of successful open source project. Git is up there too. Don&#x27;t like Github? Switch to Sourceforge. Don&#x27;t like Sourceforge? Run your own server.<p>So if you define the category narrowly enough, anyone can say, &quot;no open source project with these exact characteristics has ever had success,&quot; and be right. But because it&#x27;s been limited so heavily, the example from the past will have no predictive power for the future. You need to find a different way of analyzing the problem.