When a velodrome was built in my hometown, people were outraged. The cost was around $600k of 80's money. And there was absolutely no tradition in the area for this sport.

Less than ten years later, olympic gold:

https://en.wikipedia.org/wiki/Jos%C3%A9_Manuel_Moreno_(cycli...

The same could be said for the Manchester Velodrome, high quality facilities built in an area without much history of cycling and now we churn out Olympic medalists

https://en.m.wikipedia.org/wiki/Manchester_Velodrome

The reason for those is local tradition.

But football is the only real global sport. There's a country on every continent where football is the main sport. What other sport can claim that?

So dominating football is hard, because there's loads of other countries where local tradition is to train football.

You make a good point about football being played in many countries globally. However, regarding the point about continents, football is not the main ball sport in Australia. It probably ranks third or fourth most popular (after Australian football, rugby league and possibly rugby union), although Australia will be at the upcoming football (soccer) World Cup.

Australia moved from the much weaker Oceania Football Confederation, apparently in 2006, to a better Asian Football Confederation, better in the sense that the competition was stronger but not by much (if you put aside Iran, Japan and South Korea). Qualifying from this region is not nearly as tough as qualifying from other more competitive regions.

Australia as a country is known to spend real money on sports. They are able to produce top athletes, that's not a problem.

Australia has been able to participate in the Confed Cup and World Cup tournaments which helps boost its ranking because more points are allocated for participating in those tournaments.

Whether Australia poses a real threat to the dominant powers, that's a different story altogether. Moving to a Asia surely paid off dividends for them though.