How would you know that no one in the CW cabin was deprived from anything because of this unless you only did this at the end of the flight when the Club Kitchen was being cleared away.

The items maybe there when you took take but that would mean another pax who decided to sleep first and snack later would not have access to those food items. There is only a limited amount of snack a plane can carry so there are no surplus supplies to re-stock.

We have also have various pax here complain that the selection in the Club Kitchen is limited and complained directly to BA (and on this forum). BA then have a go at the FA.

When I am in FIRST, I would not raid the Club Kitchen out of respect to the CW pax. A DYKWIA FIRST pax might demand for more. Its a bit like asking for ice-cream in FIRST which would mean a reduction of the ice-cream stock for CW pax. Normally the FIRST meal service is takes longer than the CW meal service so the crew would know if there are any spares going after the desert orders had been taken. There is no automatic right to raid another cabin's food supplies.

Ultimately, this is all about respecting your fellow pax in whatever cabin they are in. The attitude of many posters have really been about me, my, mine, etc.