Monopolies essentially become public companies because they are too big to fail and the taxpayer is ultimately on the hook for them, as we learned back in 2007-8.
The interest of the dealers [referring to stock owners, manufacturers, and merchants], however, in any particular branch of trade or manufacture, is always in some respects different from, and even opposite to, that of the public. To widen the market and to narrow the competition, is always the interest of the dealers. To widen the market may frequently be agreeable enough to the interest of the public; but to narrow the competition must always be against it, and can serve only to enable the dealers, by raising their profits above what they naturally would be, to levy, for their own benefit, and absurd tax upon the rest of their fellow-citizens. (Adam Smith, Wealth of Nations (Amherst, New York: Prometheus Books, 1991), pages 219-220)
Notice he called monopolies an "absurd tax upon the rest of their fellow-citizens".