Earlier quoted context omitted.
There are many ways to loose control of your company without selling it upfront. For example if you take money from an minority investor with the promise of an IPO (so they can make profit from their minority share). After the company goes public, control is much more iffy. You may for example not have your place in the board anymore even though you are majority owner.
You're not making any sense. Unless the majority owner has a different share class with reduced voting rights then they can absolutely control the Board.
Either you have control of the board or you are the CEO having control of the operations. Not both.