I have only ever hosted paid plugins on private Github repos.
If you are fine with some users downloading the code for free from Github, then I wouldn’t worry about it too much. Most “normal” (non developer) users get turned off by Github because the first thing they see is a bunch of code.
I’m not saying that a large number of users wouldn’t download from Github, or that some users might promote the fact that you can download it from github, but if you have the main plugin’s site elsewhere (perhaps a dedicated domain) and you’re advertising it for sell there, most users who are interested in just using it will probably purchase it.
To help mitigate the number of non-developer users that do download it from Github, one thing you might consider is not publishing the Github link anywhere except in a “Developer’s” section of the site. Non-developer users will very, very rarely ever look at a “Developer’s” section.
Just my two cents.