You’re right. It’s also true that if I don’t wish to expend my labor power in exchange for compensation, I can also buy a factory where I buy materials and labor and sell them for more than they cost.

Can you think of any reason why, when done at scale, these sorts of activities create a class system where not everyone can simply buy a plot of land and build a house, or be an industrial entrepreneur? That there will actually have to be many times as many people who have to sell their labor and pay rent?