It's an emotional problem...some sort of issue within her. I used to go way over the top though not to that extent.
I grew up in a happy but poor family.
I married DH, who is from a middle class family...he helped me to see sense and now my DC get about ten gifts each.
I used to literally buy crap just to swell the pile. Four dolls, three different sets of lego, at least two physcially large gifts.....mine would have about 40 to 50 gifts each and that was before they were 8.