> Rewards are given for actions that help the network reach consensus. You'll get rewards for batching transactions into a new block or checking the work of other validators because that's what keeps the chain running securely. The unstated gotcha here is that the chain operates through a variation of BFT agreement where staked coins vote for new blocks. All the usual BFT constraints apply -- namely, if fewer than 66…
It's not a shocking economic situation that you can use capital to acquire more capital. I don't know exactly what equilibrium the long term staking rewards will tend to, but it's not very different from interest - where for nearly no risk your capital lodged with a bank increases. The other side is that in a healthy financial system, locking money up has a cost too, so it's appropriate to recompense those who do.