How much are j. p. morgan, j. d. rockefeller,
and andrew carnegie worth at the peak of
their power (combined worth)?

the answer is: must pay taxes on profits

since it is considered as a part of your income, profits from investments is eligible for tax payment.

the tax from your investment could be influenced by how long you decided to sell it. united states promotes keeping your investment for long term period. so, the tax rate for investments that you sell in less than one year is typically higher compared to investments that you sell in more than one year period.

they both built pyramids.

c. free trade can lead to low pay for workers in poorer countries.