...and it's not hard to guess why, when you look at the key failures of American foreign policy, in which Bolton was directly involved.
The pressure on Iran has failed. Iran did not surrendered and responded to harsh measures with harsh measures: shoot down an American drone, seized a British tanker, not only didn’t leave Iraq, Syria and Lebanon, but on the contrary continued to increase its influence and presence. Like a cherry on a cake, the Trump-Bolton policy has led to the fact that United States are now facing the risk of getting Iran with nuclear weapons, that will happen because the United States themselves withdrawn from a deal prohibiting Iran from having nuclear weapons, a deal Iran agreed with!
Campaign in Venezuela, in order to overthrow Maduro, failed miserably. Bolton was one of its main architects, so the part of the failure is completely on him. He fed Trump the idea that if he support Guaido and "these guys", then everything will work out. Trump believed and then was greatly disappointed when, instead of a quick and elegant colour revolution, he was dragged in a lengthy campaign that has led to increasing of American and Russian military presence.
An attempt to make a deal with North Korea, too, failed miserably. Trump was ready to negotiate, but the summit in Hanoi, which was supposed to be a breakthrough point, was disrupted. This was largely due to the actions of Bolton who, on the eve of the summit, several times rudely threatened Kim Jong-un while CIA organized a raid on North Korean diplomatic mission in Spain...
Bolton got off very easily. Essentially, for what he did, he fully deserve a death penalty.