People often buy domain names and only have them for email purposes, some have them so that they can resell.
Some companies will register a domain and keep it a number of years, drop it for a year, pick it up again, who knows.
One thing I can tell you is that a domain name can not be snapped up when it expires, the person that owned it has 365 days from expiry date to acquire that name again, so that means that the domain expires on 2/4/14, it is then 2/4/15 until it can be made available for general sale.