I have a question and maybe a smart Spout off reader can supply

Avalon - I have a question and maybe a smart Spout off reader can supply an answer...QUESTION is, I am reading that Social Security could run out of money in 15-20 years.Question is How come we never read that the Congressional pay roll never runs out of money..We all pay into Social Security BUT members of Congress pay nothing for their health care..Not being a Math Major it would seem social Security should last longer than Congress medical plan...What am I missing?