It should be clear by now that this is a fallacy, many open source projects have attempted to sell support but there's just not that much demand. A good product does not need to offer much support, and consulting doesn't scale. iText is a good example of an open source library that has tried pretty much every open strategy and reverted to closed-source.
By definition you're not going to make money through open source selling licenses, but you're also not going to make any real money selling something else, unless you keep some aspect of it closed, like Google do with their search indexes.
The open source software which most companies publish has nothing to do with how they make money, it's usually some implementation detail of their infrastructure that represents an incremental improvement on some similar open software which came before it.
By definition you're not going to make money through open source selling licenses, but you're also not going to make any real money selling something else, unless you keep some aspect of it closed, like Google do with their search indexes.
The open source software which most companies publish has nothing to do with how they make money, it's usually some implementation detail of their infrastructure that represents an incremental improvement on some similar open software which came before it.