The contrast between Powered up Hive and liquid Hive is stark and so is Proof of Brain at the moment. Proof of Brain tokens will reach a point in the future that will make this gap tiny. You'd be able to leave leave unsteaked tokens with a much smaller opportunity loss because new tokens would be created at a very slow rate.
Although Hive will have strong incentives to keep normal users with little Hive which allows this situation you described, on Proof of Brain down the road this wont be able to happen. Now by "down the road" I mean liek 2033.