Is it stupid to quit graduate program after one year?
Are you paying for this MA programme yourself (e.g. with student loans) or do you have a scholarship that pays for it? If you are about to walk away with debt but no degree, you should strongly consider sticking it out for the second year, especially if the issue isn't academic and you feel that you can continue to do well in your studies. Even if you are not going to be walking away with debt, consider staying on. 

While you may feel that you do not need a master's now and that it is just a piece of paper, you can't quite predict where your future will bring you. You might find yourself in a position where a master's degree (any master's degree!) will allow you to progress in you career in a way that is vastly more beneficial than if you only have a BA. To go a bit sociological on you and to whip out the Pierre Bourdieu, you are proposing you bank on your embodied cultural capital and are wanting to forgo the objectified manifestation of it; you are wanting to head off into the world without the degree. Yet this world likes degrees and may not always believe in you when you don't have them. In 10 years time, when you are somewhere in life that you can't predict now, how would you feel if not having the master's holds you back?

If you stick it out one more year you will be, at most, in you mid twenties if not still in your early twenties. You will still be young. Mid twenties abroad is just as good as early twenties abroad, and one year is not very much time to wait. Everything is the same, nothing is going anywhere, you'll just have a master's degree when you get back to it.