Deception
As Dante and the other students were about to descend, they were made to go through a set of annoying procedures first. They had to sign death waivers, stating that whatever happened while they were in the Zero Gate could not be used as evidence to find anyone liable in the real world.
Of course, this was balanced out by the fact that the agreement acknowledged the fact that anything they earned while within the Zero Gate exclusively belonged to them and no one could take it away.
Naturally, those in the know knew that this was bullshit as students might have been forced to sign other agreements by their factions or clans before this that superseded this agreement, but that was a problem for them to face, not the school.