My two cents is that VB is a language that's used for niche stuff and most of the related jobs you are likely to find (freelance or otherwise) are more likely going to be maintenance tasks: updating the software to keep it going instead of expanding it's operation.
VB is a pretty basic language, and will continue to be useful as long as Microsoft continues to keep it up to date with the .NET Core. At some point they said they wanted to continue expanding the language, as to keep it's relevancy, but as of 2020 my understanding is that it's only being updated to continue being .NET compatible (
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) and nothing else.
I can't say I'm well versed in it, and I haven't used it often in my life, but the few times I did in the past was for "scripting" purposes (VBA & Excel). If you are already investing time in C, C#, Java, Python and/or JS, I see very little benefit in going out of the way to "master" it. Other than understanding the syntax (which you quickly will) and it's limitations, you're probably done.