That takes at least a little bit of time. Can be quick, but not instant. But, based on the "wear grease" pattern on the wheel, I'd say this took some mileage to reach finality.
Think carefully about what you were experiencing in the minute, 5 minutes, and 15 minutes before the moment of terror.
A loose wheel like that causes vibration, which gets worse and worse, until it all goes bad. Even though it was on the trailer, you should have still felt the vibration, and possibly even "hopping" of the trailer. The trailer should have also been visibly shaking before the last/second-to-last lug nut or bolt let go.
If you can remember what that felt like, you should be able to recognize it if it happens again, and stop before it gets to this point.
Having experienced several tire blowouts on several vehicles, it only took me about 3 seconds to recognize the problem when I felt the slightest vibration coming from this tire. The trailer seemed to be vibrating, too; but I wasn't 100% certain. At that time, the bubble was tiny. But by the time I was able to slowly make my way off of the highway, it was about a 3" bubble at the top of the off-ramp - and clearly visible in my mirror as I made the turn. Another 1/2 mile down the road, in a totally safe place to stop, jack the trailer, and change the tire, it looked like this. I was very happy to have recognized the symptom and gotten off of the highway immediately (-ish -- the next exit was about 2 miles away when I felt it).
Brand new tire, too.
