UKIP won the last Euro elections, and promised a referendum if elected to power.
We will never know what would have happened if the other 3 parties had not suddenly offered a referendum too.

There is already a lot of anger about the "Brexit betrayal" and someone is bound to seize on it.

There is a tendency everywhere for electorates to turn against their ruling political elites who ignore them.
That is not scare mongering. Look at EU, USA and the referendum here.