RSR

How did he know

The purpose of rsr is to use it as arbitrage for RSV. If RSV rises about 1.00, i.e 1.02 RSR tokens can be purchased and used to arbitrage until the price of RSV is back to 1.00. Traders and speculators can use this to make consistent gains when RSV fluctuates. So yeah RSR actually has a solid utility unlike most other coins

But a stable type coin has never been worth 10 billion.
Not even maker
What makes us better than
maker dai?

It doesn't have to be worth 10 billion to see huge gains. It could potentially be worth that much at one point, but it's impossible to know how succesful RSV will be as of now.
Arguably RSR/RSV is better than maker/dai, because of the different ways of stabilizing. Dai has not been close to $1 on multiple occasions. Also RSV should be easier to use for the normen.