They compare people to the Klan and threaten corporations that fund those people they don’t like. Essentially “we’ll brand you as Klansmen”.
Liberal idiots likely donate a lot to them, but I think you have nailed the secret of their success. SPLC has become a shakedown, a la Operation Push, with protection from corrupt Dems who dominate the IRS. Offshore accounts make no sense for an honest non-profit.