"One could come and take the cup..."

In the Bazaar. Not on Hive.

When you upvote, downvotes can counter your upvote. When you click the 'gift box' and send a tip, downvotes cannot counter that tip. In seven days you can receive the full amount of the tip and secure it in your wallet.

"...DV because, that's just what is coded in..."

DV's cannot take your tips. They can only take your upvotes. They cannot downvote your wallet, only your author rewards prior to the seven day period being over and those rewards being available to you to put in your wallet.