Self-storage is an increasingly popular business. There are an estimated 45,000 storage facilities across the country, and new construction has tripled in the past five years. There is now an estimated 6.5 square feet of self-storage space for every person in America. Households, not companies, account for 80 percent of industry revenue of $38 billion a year.What is marketed as affordable convenience comes at a high cost, and masks an oddly American appetite for stuff.