Your hobby will apply fine in any field--buy low, sell high.
I actually enjoy filing my taxes
"Son, you have a condition." --quote from the Avengers.
You may consider being an expatriate and working for a non-US company in a non-US location. Then, you can file and pay taxes both for the US and for the non-US nation.
so any corporate discipline that doesn't require specific academic training (like engineering or computer science) is probably attainable via the MBA 'career reset'.
Not really. In my experience, it's the other way around. An MBA is useless unless you've earned your value in a field that adds value (one of those specific fields). Anybody else, is mostly just full of BS, and can only thrive when they're surrounded by stupid people who don't know any better.