If a program specifically forbids such practices and you have agreed to the membership conditions, then such things are indeed fraudulent. You are deceiving the company to get financial gain. That said, I personally view this as a lighter case of fraud the miles were legitimately earned by someone else.

Also if I were to buy an upgrade or miles from a program to which I do not have membership, I do not think it could constitute fraud since you have never agreed to any terms and conditions.

I am open for thoughts from others.