Earlier quoted context omitted.
What if my car breaks down? That doesn't mean that cars were a bad idea, just that I have a crappy car. Do you have any reason to believe that Coin will be any less reliable than a regular credit card?
Yes, how about "many merchants won't accept it". Or "the battery runs out after 1 year."
Many merchants I swipe my own card and they never see it. A waitress may question it, but I have no reason to believe they won't accept it if it is validated by their card reader.
The website says the battery should last two years.