As smelly as Trump's many conflicts of interests may be (and we'll never know the half of it), he will be far from the only U.S. president to have enriched himself through his official actions.
The worst offender is someone who is still, strangely, regarded by many as a champion of freedom and democracy: Thomas Jefferson, the second president and one of a long string of early presidents to who represented the interests of the Virginia plantocracy.
Thomas Jefferson was highly conscious of the ways in which his wealth increased as long as enslaved women could be made to produce a new baby at least every two years.
Jefferson, who owned over 600 enslaved persons during the course of his long life, was highly conscious of the ways in which his wealth increased as long as enslaved women could be made to produce a new baby at least every two years. In 1792 he wrote a letter to George Washington marveling at this "automatic" increase, and he continued in creepy fashion to do the math on black bodies until his death in 1826.
This notoriously spendthrift man was naturally at pains to keep the price of his "property" high. Slaves were his main source of credit. Jefferson was among the first racial theorist to refer openly to enslaved African Americans as "capital" and sometimes as "stock."
As lands to the west were opening up at the very time that the transatlantic slave trade was shutting down (Jan 1, 1808 was the deadline to end the African trade), there was fierce competition between the Tidewater states of Maryland and Virginia and the Low Country states of South Carolina and Georgia to see which could profit the most from the now-immensely-profitable internal slave trade. As the president who made the Louisiana Purchase in 1803 (ironically a huge windfall for the slavers that was triggered by the massive slave uprising in Haiti that had so unnerved Napoleon), the crafty Mr. Jefferson saw to it that the colossal new territory would be run for almost ten years as a dependency of Virginia and that Virginia slave breeders (such as himself and his relations) would reap maximum profits from shipping their "stock" 1000 miles to perform the excruciating labor of clearing fields and hoeing and picking cotton.
Yes, it's true that Jefferson died in debt. But he could not have lived in such high style at Monticello for so very long had it not been for the wealth and credit he enjoyed as a slave breeder (literally, in his case). He knew full well that that his wealth and credit had been secured by his official actions as president.
Jefferson was probably the worst. But a dishonorable mention should also go to James K. Polk, who provoked a war with Mexico with the clearly-stated intention to annex Texas as a slave state. While President Polk was orchestrating the Texas deal to ensure a rising price for human flesh, he was simultaneously trading slaves from the White House through an intermediary.
It is said, falsely I think, that U.S. Grant sold government favors while in office. Even if that were true, a little bit of Gilded Age graft is nothing to compared to the traffic in black bodies that the planter presidents (and their many northern enabler/collaborators like Martin Van Buren and Franklin Pierce) applied themselves to with such sustained diligence over the decades.