I listened to the book Protecting the President by Dan Bongino, to get a sense of how risk management works for US presidential protection - a risk that is high-stakes, where failures are rare, where the main threat is the threat from an adversary that is relatively hard to model, and where the downsides of more protection and its upsides are very hard to compare.

Some claims the author makes (often implicitly):

• Large bureaucracies are amazing at creating mission creep: the service was initially in charge of fighting against counterfeit currency, got presidential protection later, and now is in charge of things ranging from securing large events to fighting against Nigerian prince scams.
• Many of the important choices are made via inertia in large change-averse bureaucracies (e.g. these cops were trained to do boxing, even though they are never actually supposed to fight like that), you shouldn't expect obvious wins to happen;
• Many of the important variables are not technical, but social - especially in this field where the skills of individual agents matter a lot (e.g. if you have bad policies around salaries and promotions, people don't stay at your service for long, and so you end up with people who are not as skilled as they could be; if you let the local police around the White House take care of outside-perimeter security, then it makes communication harder);
• Many of the important changes are made because important politicians that haven't thought much about security try to improve optics, and large bureaucracies are not built to oppose this political pressure (e.g. because high-ranking officials are near retirement, and disagreeing with a president would be more risky for them than increasing the chance of a presidential assassination);
• Unfair treatments - not hardships - destroy morale (e.g. unfair promotions and contempt are much more damaging than doing long and boring surveillance missions or training exercises where trainees actually feel the pain from the fake bullets for the rest of the day).

Some takeaways

• Maybe don't build big bureaucracies if you can avoid it: once created, they are hard to move, and the leadership will often favor things that go against the mission of the organization (e.g. because changing things is risky for people in leadership positions, except when it comes to mission creep) - Caveat: the book was written by a conservative, and so that probably taints what information was conveyed on this topic;
• Some near misses provide extremely valuable information, even when they are quite far from actually causing a catastrophe (e.g. who are the kind of people who actually act on their public threats);
• Making people clearly accountable for near misses (not legally, just in the expectations that the leadership conveys) can be a powerful force to get people to do their job well and make sensible decisions.

Overall, the book was somewhat poor in details about how decisions are made. The main decision processes that the book reports are the changes that the author wants to see happen in the US Secret Service - but this looks like it has been dumbed down to appeal to a broad conservative audience that gets along with vibes like "if anything increases the president's safety, we should do it" (which might be true directionally given the current state, but definitely doesn't address the question of "how far should we go, and how would we know if we were at the right amount of protection"). So this may not reflect how decisions are done, since it could be a byproduct of Dan Bongino being a conservative political figure and podcast host.