If I am China I lend you money I would like get paid back in dollars because I can already print as many Yuan as a I want. Why should I lend to you in a currency I can turn the printing press on for. So it feels like the Dollar will be around for awhile as long as it is accepted, convertible, and the Government tries to slow down the printing press themselves.
If you pay me back say in Pesos and I can print Pesos then did you really give me anything at all because I have more all for free.
If I own a teddy bear factory and I give you 10 teddy bears and you give me back 11 teddy bears I would prefer 11 dolphins instead as they are something that I don't have and can't make.
To get those pesos to pay you back, he needs to get those pesos, which means selling you something and then giving back the money you used to pay for it, which means the real interest you got was those goods. That's real value that diluting your own currency doesn't get you.
The Euro already is the second reserve currency of the world, and because it's already an international currency, no single country can just decide to print more. It's a far more attractive choice than the Yuan or arguably the Dollar.
