For the heroic adventurer on the move, having a static place of residence is impractical. You have to pay someone to keep an eye on it while you're off for months, even years at a time, gallivanting across the galaxy, else you run the risk of something going wrong, like your gas leaking and causing a cataclysmic explosion. You also need to pay someone to tend the lawn, else the HOA will be on your case about lowering their property value. In a nutshell, home ownership is a pain when you're not living there 90% of the time. That is why one's ship is as much a home as it is a way to get around.