Which new stablecoins are coming out in 2019?

How does a person know that the stablecoin is not a scam and is audited/verified showing its backed up by something? For example USDT suppose to be backed by dollars in a account/vault. Can the buyer go to the vault and exchange his/her stablecoins for whatever it's backed by in the vault?

If stablecoin crashes and dies will buyer/hodler be compensated?

Which stablecoins are decentralised and is regulated by the government?

Why would someone by a stablecoin? Is it because it is more convenient to hold compared to the actual physical thing?

Finally how do you make money on stablecoins on the markets if there are no bull or bear markets or volatility for them?