No, consider it property taxes.
In the real world, if you own a house, you pay yearly property taxes.
In this game, a year takes place in about 1 week, though your hero doesn't age and die off.
That your rent (100 gold) is 20% of your original purchase price (500 gold) is a bit steep. However, if you pay 1000 gold for the first storage upgrade, then your total house value is 1500 gold and your rent is 196 gold. So, your rent is 13% of the total value each year. If you pay for the next storage upgrade of 3000 gold, the rent becomes an even smaller percentage of the total value. It pays to upgrade and moving is very cheap, 100 gold ... and you save on relocation and moving expenses. Note that cheap means, you can earn 100 gold pretty quickly from fighting in a dungeon, selling a crafted item or two to the shop, or on the market.
Bank interest is earned weekly, too. (7% wow! that's much higher than we're getting in the real world.)
