shanyee - unfortunately because you don't have a good track record with USDM. That's the very simple answer.
You had run ins with them over your 11 segment ticket - calling almost every day - sometimes multiple times per day asking for routings you knew you weren't allowed (people advised you of that). You chose however to ignore those who told you to move on, and clung only to the few people who told you to keep calling. Basically you wasted a whole bunch of US reservations agents' time. Time costs money and causes delays for everyone else tryng to get through.
You got angry at USDM and Thai about not allowing the infant to fly in business class. Even though you got all four of you on Egyptair you still complained. (A big thank you should go to Egyptair for having seats available at one day's notice and aving yourwhole trip).
You have multiple accounts, at least one of which (you mother's) you were using for nothing but a vehicle to earn more miles than you were allowed to have.
You paid less than the required number of miles for one of your trips... 45K instead of 140 or 150K?? Did you tell them about the mistake and have them correct it? No. They would have had to pay the other airlines for those seats and you still kept your miles to use again (they were out of pocket!!)
You sold a ticket to someone else.
You earned miles via promotions you were expressly prohibited from earning miles through (the USDM search tool - the rules of which were expressly limited to residents of the USA and Canada or something).
There are so many reasons why they might have looked to close your account.
But what is done is done. I know you were very excited by the opportunities offered by these promotions, but there is a way to take advantage of these without going outside the rules. I think US has been very patient.
Any one of the above things I'm pretty sure US would have overlooked. But once you start to add them up they become an issue.
This is not a personal attack against you, this is just stating some of the issues. If you don't get any miles back, then maybe take away some of the lessons and apply them to your other dealings with the Intercontinental hotels best rate guarantee, or with other airlines as you buy miles there, or seek to have a status match, or seek lounge access you are not entitled to. Keep your head low and keep enjoying the possibilities!