I was just reading up on the EU's budget here, and the net loss that France, Germany and the UK get from the upkeep of the organization is astounding:

http://en.wikipedia.org/wiki/Budget_of_the_European_Union#Traditional_own_resources

Does someone they don't have to be European, want to explain to me why these three countries in particular continue to support the EU?

Ze power.

Well for one, access to the giant market the EU created, so that any country that's not in the EU is at a disadvantage when trading with the EU.  I actually believe if you want to sell a product in the EU and aren't part of the EU you have a big tarriff placed on it.

So if France left, it'd hurt their trade quite a bit. 

Also, in general France is a much bigger player in the EU then it ever was with NATO... so it gives them a certain amount of poltical sway, note how the EU stopped their Roma expulsion investigation. 

They'd lose their free travel rights.

Oh yeah and France also gets HUGE farm subsidies.  Not sure the CAP is reflected in that.

Not all nations get a net gain from the EU membership but we want to be part of it and help the vision of uniting Europeans which ultimately will lead to the USE, United States of Europe.

Better athletes and women.

For Germany by the way, I imagine that the advantage is free trade of their products to the rest of the EU markets due to being able to control trade regulations in other countries.  They're paying upfront for a backdoor advantage at selling their products and probably more then make up for the cash paid out via GDP growth because they end up being cheaper then American made products, and well priced to Chinese products when you add on the tariff and consider the quality differential.

The Uk.... that's a tough one.  What with the UK being stronger in NATO... but that's probably why the UK has always been less EU friendly then rest of Europe.  Still, probably mostly strongarmed into it due to fear of economic isolation from the "EU first" trading policies.

United States of Europe it is not and never will be. There is just too much history and clashing of cultures for the EU to ever be more than an economic pact where, from time to time, the wealthier, geographically west and northern EU members bail out those members who are more eastward and southern.Besides the currency, I don't really see many benefits besides collective bargaining as a group of countries. The UK, all of northern Europe, France, and Germany will always give more to the EU than they get back in comparison to say, Greece. There are exceptions such as Ireland who is north and west geographically, but shares more in common with a bad economy more comparable to Spain than the UK.

If you look at the US, you find a similar pattern where the coastal states tend to give more to the Feds in taxes, while states such as Mississippi, Alabama, and Louisiana annually take more in Federal tax dollars. This giving and taking of tax dollars from the Feds is all dependent on individual state average income levels as shown in my source below.

Source: www.childpolicy.org/whatsnew/RichStatePoorStateRedStateBlueState2005.pdf

A book was written by Andrew Gelman who is one of the authors from the source I cited. The title is Red State, Blue State, Rich State, Poor State: Why Americans Vote the Way They Do. Briefly, what Americans think of Blue States (vote Democratic in Presidential elections) are wealthy, thus they give more in taxes to the Feds than they take; Red States (vote Republican in Presidential elections) are poor, thus they take more in taxes from the Feds than they give. There is more to it, but I have digressed too much.

The United States of Europe won't happen because it's exactly like the United States of America... which exists.

I don't think you've digressed so much as started your own counter arguement against your point.

Don't underestimate the advantage of having a bunch of poorer europeon "states" to have full control over because they need the money... making sure they buy German and French products, and that their building efforts are done by german and French companies, with loans made from german and french banks.... etc.

They can use those countries kinda like China uses some of it's areas.

Build it up economically, but make sure that the benefits of the economic growth mostly benefit Western Europeon states.

EU has advantage and disavantage for France

the initial idea of french political was to build an UE that would be independant of the US/OTAN

of course, it didnt happen ....

now, we have open the door to many new country that are pro-american and that are reducing our independancy without giving us many advantage

we are just some others US dogs .... 

Not all of it is bad, nor is the US aiming for a poorer, southern state such as South Carolina to secede like John C. Calhoun advocated for in the antebellum era.

As for a counter-point to my own point, I just don't see it. I was illustrating the wealth and geography theory I laid out in my original comment here. Alabama shares a lot more in common with California than Poland does with France or the UK in terms of shared history and culture.The history I am most aware of is the centuries of conflict between the european states prompting the US and UK to agree to the Monroe Doctrine concerning the Americas.

What the EU does is tie all of Europe together whether Germany, France, or the UK likes having to increase their share to help Greece out or not. I am not one of those EU doomsayers with a calendar on my computer counting down the days until the EU will dissolve. Instead, I understand the economic importance that ties them all together.

The interesting point is a country like Turkey. Is it foreseeable with the plight of Muslims and nativist reactions in European countries to ever accept a Muslim member into the EU? I think it will happen, but it may take another two decades.