Comment by uiri

If you are the copyright holder, you can do whatever you want with the software. You don't need to obey any license since you're the counterparty for anyone accepting the license. If your premise is correct, and open source projects have become dominated by tools, libraries, etc that support a proprietary end product, it would make more sense to me that most of those tools would be released under the GNU GPL so that the original author can incorporate it into their own proprietary software but no one else can do the same and the original author gets back any improvements contributed by outside parties.