I have read that interest was banned by the christians so only the Jews could do it. But why did people decide to take loans from the Jews when that meant they would be charged with interest rates? What did the Rothschilds have that they could leverage into a deal?
I have also read that the Jews were segregated into an alley in the Holy Roman Empire. Obviously they were considered “lesser” and had less rights. What if a politician decided to take a loan from them and then cheat them. For example not paying interest or not even paying back the loan at all? I feel like it would’ve been easy for a rich politician to screw them over and get away with it.
I have read that interest was banned by the christians so only the Jews could do it.
In the Middle Ages and even Early Modern period, that would be correct. That is not at all correct for the early 19th century when the Rothschild bank was founded. By that time, commercial loans with interest were commonplace in west Europe and many commercial banks existed. Even many that remain today like LLoyds bank. (which was set up by Sampson Lloyd, who was a Quaker, should it matter), which is over a half-century older.
What did the Rothschilds have that they could leverage into a deal?
There is nothing particularly special about the Rothschilds except the extent to which they've been the target of antisemitic conspiracy theories that distort facts to try to claim there's something special about them.
(For instance another post I answered on this sub claiming they were unique in having kept their wealth, despite all available economic-history research arriving at the entirely opposite conclusion that most families wealthy 200 years ago remain well-off.)
Already the premise that it's somehow legitimate to talk about a whole family as if it were a monolithic entity working in concert to specific goals, is conspiratorial, dehumanizing and implicitly antisemitic.