Back in 1997, Robert Kiyosaki wrote a book about personal finance called "Rich Dad, Poor Dad" that became an instant best-seller. Among Kiyosaki's most important points is that the process of building wealth is difficult because many people fail to distinguish assets from liabilities. For example, most people regard owning a home as an asset, but when you add up taxes, depreciation, insurance, mortgage payments and the vagaries of an ailing housing market, it's clear that homes more often behave like liabilities than assets.