I was originally interested in my local state school only but then I got a 521 MCAT, so I applied to a few T20s just to see if they'd accept me. I'm still in undergrad right now, but if I don't get in this cycle (assuming my administrative resolution isn't too damning), then I'll probably blanket the street with applications like most other people on this forum next cycle to make sure that I get in somewhere. Also, money was a practical concern for me on secondaries at that point.
edit: sorry misread your question as 'why did you only apply to 7 schools?'