As I've said before, anyone who claims that X made or lost money has no clue. Measuring the economic impact, revenues, spending, etc. of an event like this is impossible to do. There are a few reasons for this:
1. Infrastructure spending - Are improvements to airports, highways, public transit included or not? should they be included if they were going to be done eventually anyways?
2. Revenues - Are we just counting tickets sold? Merchandise? How about tax dollars accumulated from hotels, restaurants, etc? How do we know if a dollar spent was directly caused by the Olympics? Are we measuring tax revenues from every level of government? What about tax dollars stemming from multiplier effects (which can't be measured accurately anyways - see pt 4)
3. Economic impact - When do we start measuring and when do we stop? If I watched the Sydney Olympics 10 years ago and thought "hey, I never knew Sydney was so cool. I'd now like to go to Sydney" and saved my pennies and left tomorrow, would that be counted? It should be.
4. Multiplier Effects and leakages - Multiplier effects are impossible to accurately measure. Tied into this is the concept of leakages. Does the money spent in Toronto stay in Toronto, or is it transferred to a head office elsewhere?
5. No two events are measured the same way. You won't be able to look at Athens and compare it to Sydney or Vancouver. Different arrangements, governments, private investments, etc. mean that some things are reported and others aren't. So it's impossible to accurately compare and contrast success or failure.
6. Pre and post-games events - Most stadiums built for Olympic events hold pre-games and post-games events. Are these counted? If they are counted, wouldn't the economic impact be infinite? I mean, you can't project ahead 30 years to the day when that stadium maybe hosts a World Cup match. Furthermore, just because a stadium isn't being used today doesn't mean it won't have a good use tomorrow.
There's other points but I think that's a pretty good start for why we people are so far off the mark when it comes to talking about the financial realities of mega-events like the Olympics.