I'm still waiting to read of even a single example of a full-time employee who is working on (not preparing for) a business of their own while collecting a full-time salary. If it's such an awesome thing, there must be dozens of examples to choose from, right?
Why the silence? Because that employment arrangement does not work, and any person running their own full-time business would know why.
Working as a contractor while getting your business up and running? Great! That'll work fine.
Working as a full-time employee while starting a business? Doesn't work.
If you walk the talk and start your own company, you'll understand why you wouldn't want to be paying a person out of your own pocket while they're going through that process.