The FBI doesn’t prosecute powerful politicians. Their goal is to obtain information on whoever is in power to hold it over them. This gives the leaders of the FBI power. It has been this way since Hoover. That is why he could stay in power through so many administrations. They didn’t want to prosecute Trump, they were looking for dirt. Trust me, they already have plenty on Biden but he will never be prosecuted either, unless he doesn’t play ball. And he will.