I don't get what the OP means . The name stable coin says that they are stable with some form of Fiat mostly USD . So you are not getting anything by investing in stable coins.
lol, your post got me cracking
, i guess the op is not fully aware about the nature of stable coins or he must misinterpret what he meant, whatever the case maybe, it has been said already, stable coins are not for investment rather they are mostly for preserving what you have, i think op needs to go back and do some more reading or we need to do some more reading. 
He also includes Titancoin in the list. I'm not really sure how this titan coin to be considered stable since I'm not seeing any token paired to titan at all. But then you must have realise by now that he had been shilling for this project since time.
Stablecoin isn't really for insvest like you said. Its just for hedging the coins in case the prices will dip like what happen during the bear market of 2018. Stablecoin are safe though.