100000 lines is probably an underestimate. Doing a line count on all the files in my development directory, I find that I've got about 35000 lines of code in there, and I still consider myself somewhat of an amateur (I've been coding for about a year now). I code probably five hours a week or so, so a full-time programmer with similar productivity who had been programming for a decade would have written 2.8 million lines of code.

100000 lines sounds like a lot, but it's really not.