ddos can run over a rather long period of time and come and go fairly quick. cutting the internet connection just is no viable solution for an online service.
Your analogy is wrong. A riot inside your store would be a compromised server. What you want to do is to close your store every time someone who looks like a burglar walks by, in front of your store. After no time the competing store on the other side of the street will hire an actor to walk by your store and shut you down just with walking in front of your store.
It's super easy for every competitor to get you out of business forever if you just shut down. DDoS is not like something especially hard or expensive to set up (depending on your service of course), but again, shutting down is not an option as a standard countermeasure.
How would an attacker exploit a service while it was inaccessible because they're DDoSing it? Why would someone draw attention to themselves like that?
Maybe the attacker stole the coins and then DDoS'd the site?
It's all speculation, we're pretty light on details, but the whole DDoS-as-a-distraction thing seems a little out there to me.