You can only sell scarcity. No one will pay you if they don't have to. People are funny that way.
MIT license doesn't create scarcity at all. There's no reason to pay for MIT licensed code because everyone has the right to use it for free, no strings attached.
There are businesses build on dual-licensing GPL but it pretty much only works for libraries that are part of software that would be distributed, like desktop software or mobile apps. An example of such business is mupdf PDF rendering library.
It works for re-distributable software because GPL would force the user of mupdf library to open-source their whole app under GPL as well, which is not possible for commercial apps (remember, they also sell scarcity). So they can either spend years writing equivalent of mupdf or pay a commercial license that lifts GPL restrictions.
That doesn't work for stand-alone, server side software. If the value is in the product itself, I can install GPL-ed software. I don't get any additional benefit from paying for a different license. There's no scarcity.
Selling support only works for very complicated software, like Cassandra, sold to companies that are big enough that they can afford to pay a lot of money for peace of mind.
You have to decide what you value more: writing open source software or making money.
If making money, then stay away from open source. It's not impossible to make money, but making money from commercial software is very hard and making money from open-source is 10x harder than that.