With an ETF you are not gambling on one particular company, you are gambling on one particular sector of our economy.
If you feel that real estate is oversold, and you feel bullish on the sector, you would buy the Real Estate ETF 2X Long and your money will double the performance in that entire sector.
If you feel that real estate is still going to decrease with the foreclosure boom that is on the rise, the increase in unemployment, and the ineffectiveness and the Governments modification plan, you would buy the Real Estate ETF 2x Short and your money will go up if that sector goes down.
The ETFs in the IBOX are mostly 2X leverage. FAS and FAZ are 3x leverage. When you are correct - you gain more then a 2x ETF, When you are incorrect - you lose more.