As someone in the comments just said, the DOJ used the same tactics that it uses in taking down mafia kingpins.
The evidence against the guy at the top who insulates himself is hard to get.
If they started with Trump the evidence would have been even HARDER to get.
Imagine this scenario:
March 2021: Garland announces an investigation into Trump.
Getting the evidence requires piercing attorney-client privilege and getting prominent Republicans to testify against Trump. . .
8/