Nothing to do with "Brexit" Stu, I have socialist friends who are anti and one or two who are pro.
This issue crosses party or political divisions.

The issue is how the country should be run given the large number of problems which now affect the economy, the change in demographic in the population , our ability to compete in "globalism" etc.

The "liberal left" have fooled themselves into thinking that the present economic system can be made to work fairly when in reality it requires extreme inequality to survive and prosper. Under the correct circumstances it can prosper and some of that prosperity "trickles down" but the effects are transient and in the long term bound to fail the mass of the population
Socialists are aware that the whole edifice requires to be demolished and re-constructed few are under the impression that this will be quick easy or pain free.......but it is a necessity.