1- Costs of operating an larger house are higher than a smaller house 2- Yearly maintenance of a new house is cheaper than an older house (older the house, the greater this gets) 3- Easier to keep a smaller house tidy 4- Mobility/lifestyle issues. 5- Indifference towards resale value

Not everyone wants a giant house, and plenty of people like a small one. It's not the size that matters, it's how you use it.