Money grows on both your savings and the interest already added — and that same logic applies to long-term wealth decisions like buying versus renting. This project models mortgage payments at different down payments across 15-year and 30-year terms, using real prices for recently sold and rented homes and apartments in the same area. When you factor in salary growth, rent increases, and property value changes over those long periods, small early differences in down payment or loan length compound into large wealth gaps. The results show that purchased apartments build the most wealth over time, while rented homes build the least — and a higher down payment sharply reduces the total interest paid.