I'll agree that for a large subset (France, Germany, Belgium, Denmark, Poland, in particular) the EU has indeed been a successful experiment. It was also successful for the UK until they deluded themselves into leaving.
And if the EU decided to either (a) not expand as widely as possible or (b) not try to morph into a Federal Government of Europe, it would probably remain successful indefinitely. For now the EU has been established for a blink of an eye, relatively. Only time will tell how successful they can be in the long term.
Hungary's only been in Schengen since 2007, and in the EU since 2004. In that time their GDP has tripled, and there's a huge jump over the accession period (which, oddly, flattens out when Orban takes power). Public debt hit a peak in 2010-2011, and is now 20% below that point. It's hard to see the economic effects as negative, looked at in isolation.
Hungary has its own problems that the EU isn't positioned to solve. That's not evidence that the EU itself is a failure, or bad for states that join it.
The union has been extremely successful for Spain, Italy and Portugal too, on many aspects. It forced local administrators to shape up in ways that were unthinkable before, and instilled into people that they should expect the same standard of life in Rome as in Stockholm. The long-term effects of this change of attitude are immense - systemic corruption in Italy has gone way down, environmental conditions have improved dramatically, connections and mobility have boomed. The Euro is not perfect but it wiped the periodic waves of heavy inflation that used to hit the working classes, and its worst excesses are slowly being addressed.
Has it though? Because Hungary begs to differ.
I'll agree that for a large subset (France, Germany, Belgium, Denmark, Poland, in particular) the EU has indeed been a successful experiment. It was also successful for the UK until they deluded themselves into leaving.
And if the EU decided to either (a) not expand as widely as possible or (b) not try to morph into a Federal Government of Europe, it would probably remain successful indefinitely. For now the EU has been established for a blink of an eye, relatively. Only time will tell how successful they can be in the long term.