I believe that 98 percent portion is wildly incorrect. There are thousands of small farmers and medium farm operations scattered around the world. Also, a corporation by definition can be a company with 1 or 2 people, all corporations by definition are not multinational conglomerates. So while purchasing some food items from a few companies might trickle back into one central corporation, that isn't true for all purchases being made. If you want to grow your own fine, but don't waste your time trying to shame others who might want to buy.

Did you make all of the clothing you have on right now? Did you build your computer from scratch? There are thousands of items in your home right now you didn't make and won't make in the future. So ease off a bit maybe on the pressure for others to align themselves to your view of what is or isn't acceptable commerce.