Proof of work is not a financial instrument. Proof of stake means the holder gets paid additional stake for holding. Same as in a savings account.
The fact that this is a cryptocoin does not make any difference. It is a negotiable item, which earns interest, and is being sold by unregistered persons. It is no different than buying a bond.
PoS coins do no earn interest. None.
What (potentially) earns you coin if you secure the network. To secure the network you have to have coin.
There is no new coin introduced to the system, the already existing ones only get suffled around.
I'm afraid the only place this resembles a behavior of a bond is in your head.