Because sometimes you will come home from vacation and find that they have actually moved into your home while you are away, and have no real intention of ever leaving. And you may come in to find that they have entirely reorganized the extra "bedroom" which is really not meant to be a bedroom, but the room that contains the wine closet. The suitcases that accompanied their arrival, which look like they contain enough clothing for a year and not a month of freeloading off of you, will have been emptied and organized by color into your closets. Your food and champagne bottles will start disappearing at a much faster rate than you remembered.
This is of course what I have chosen to do for the month or more that I essentially have no place to live. Apparently "I don't know" is not a very well thought-out answer to the question "Where will you be living in a week?" This may have been an oversight on my part. But my bedroom has a wine closet in it and if I stick my head over the balcony railing I am pretty sure I run the risk of being knocked out by a passing sailboat. Of course the easiest way to get me to move out would be to stop having wine delivered to my bedroom.