You're very right. West Ham are still Premier League (like Greece being a EU member)... then benefit from the single EU currency...
However, they're in the process of taking a serious hit. Greece's credit rating declining (so can't reorder its own economy) and West Ham may be relegated altogther!
Other EU countries are not happy about it and they may be in breach of treaty.
West Ham were at risk of going into administration and still may if they get relegated due to reduced revenues.
However their standard of living, and reflection of public spending will be reducing over the next couple of years to more like Bulgaria....
as a result as money is used to pay back foreign creditors and leaves the Greek economy altogether.
West Ham won't be able to invest in their playing staff and have greater difficulty keeping hold of playing staff and their competitiveness will decline. They'll be more like a Championship club as a result as they'll be forced to sell off players to pay off debts.
Abit like Greece having to sell off profitable assets to repay debts in timely fashion.