It's very unlikely that any in this number fall into that camp. The terrorists don't want to draw attention to themselves and want to re-enter the USA.
The people surrendering their passports are high earning entrepreneurs. The problem they have is two fold. They pay taxes on their earnings in the country they are in and pay taxes on their earnings in the USA. I'm not sure if it applys to personal returns, but if they file as a corporation they can get a $90,000 tax exemption but then they will pay corp. tax rates in both countries. The second problem they have is most banks are not to eager to take American customers because of the reporting requirements and consequences they face if the customer doesn't accurately report their income.
So if your overseas and see that the USA is becoming a banana republic why continue paying taxes twice.
My son is an expat. The country he is working will not give him a passport, but next year he receives a residency card. Once that happens I seriously doubt he will return to the USA. Right now he is protected from USA income tax so he sees no reason to give up passport. He already receives free medical care plus he purchases private insurance. Unless it is an emergency or a bad cold or flu, he uses private insurance. Not a bad system we should dump Bozocare for something similar.