An enlightening article in Al Quds reveals two interesting phenomena.
There are tons of aid, sent by Arab countries and meant for Gaza, that Egypt let rot for months in a stadium in El Arish. Rice, oil, blankets, flour and clothing have been sitting there.
Until it starts going bad.
Then, the Egyptians burn it.
When the poor people of El Arish got wind that this was happening, they started taking the doomed goods for themselves, overwhelming the guards.
People in the Sinai have always been resentful that they are poorer than Gazans are and yet the Gazans get free food and clothing while the Egyptians just get poorer. This is one way they feel they can get a little bit.