Olympic budgets, bottomless pits?

What explains the compulsion of politicians to waste tons of tax dollars on the Olympics. Promises are made and broken with regularity, protests are not listened to.

This year, 2006, Montreal is paying off its $2B debt for the 1976 games.

The Olympic Games have changed from an idealistic amateur sports event to a corrupt business venture that includes professionals.
Many top athletes are using hidden drugs; the honest amateurs don't have much of a chance.
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Vancouver increases budget for 2010 Winter Olympics

OTTAWA, Feb. 3 (Xinhuanet) -- Ballooning construction costs have boosted the budget of the 2010 Vancouver Winter Olympics by 23 percent to 580 million Canadian dollars (about 504 million US dollars), a senior official said on Friday.

http://news.xinhuanet.com/english/2006-02/04/content_4133473.htm

http://observer.guardian.co.uk/business/story/0,6903,1646392,00.html

Montreal massively overspent on the 1976 Olympics, following Mayor Jean Drapeau's adage, The Olympics can no more lose money than a man can have a baby.
However, with rampant corruption, and lack of financial controls, Montreal did indeed lose money, over $2 billion dollars (US), when it was all said and done. This is known colloquially as the Big Owe. As of early 2006, Montreal has finished paying its Olympic debt.

http://en.wikipedia.org/wiki/1976_Summer_Olympics