My former sales coworker owns and runs a real estate business on the side. It’s the whole nine yards: acquisitions, leasing, development, etc.
He’s fucking loaded with wealth from it and mostly screws around at work to get his paycheck. (He sometimes does his job, but it’s mostly just checking in with existing customers.)
But he says the key is to never make it sound like your loyalties are somewhere other than to your employer. Instead, just call it a “hobby.”
So he calls it his “housing-restoration hobby.” LOL.