You're reading the charts correctly. A significant amount of HIVE is indeed held on Upbit. While it's not inherently a bad thing, it does mean that these exchanges have a considerable influence over the HIVE market. It's always wise to keep an eye on large holders, but remember that users probably choose to keep their tokens there for trading purposes.
I don't blame them actually... hive price pretty much very slowly goes down as people cash out their rewards BUT we have those random days where we spike 50%-100% within hours making for some great trading opportunities.
I doubt the exchanges will do some "hostile takeover" move... Justin Sun pretty much lied to the exchanges saying there was an attack on steem... either the exchanges were like "oh ok sure what do you need" or they actively chose the wrong side. Anyways best to keep the past in the past and keep building towards the future while always keeping an eye on everything