The intelligence services are really clever in getting the information they need. Often, just like with other forms of security holes, they just need to be clever exactly once, and that might lead to months or years of intelligence.

I also think of intelligence agencies are a little like magicians in how readily they will exploit someone's trust in reality.

Right. Considering that calls can be intercepted at either end, just securing his end does not preclude the call from getting compromised on the other end. Maybe that is why the security people are not pushing back that hard, since it is fairly hopeless to limit him to only speaking over secured lines. Sure it is easy for him to access a secured line, but not the friends he wants to talk to.

> Maybe that is why the security people are not pushing back that hard

And I quote:

"Mr. Trump’s use of his iPhones was detailed by several current and former officials, who spoke on the condition of anonymity so they could discuss classified intelligence and sensitive security arrangements. The officials said they were doing so not to undermine Mr. Trump, but out of frustration with what they considered the president’s casual approach to electronic security."