Which new stablecoins are coming out in 2019?
Facebook.
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?
Then choose only corporate stable coins like USDC and Gemini dollar.
If stablecoin crashes and dies will buyer/hodler be compensated?
I'm not sure about the policies of these but I don't tnink so.
Which stablecoins are decentralised and is regulated by the government?
Those corporate stablecoins.
Why would someone by a stablecoin? Is it because it is more convenient to hold compared to the actual physical thing?
To save his money for the meanwhile by converting his total assets to a stable coin.
Finally how do you make money on stablecoins on the markets if there are no bull or bear markets or volatility for them?
Movements in stablecoins aren't that much maybe you can earn from it if you have hundreds of thousands to millions of it.
Most of the time the movement there is just cents.