A Hammerstein Ballroom stage collapsed under the pressure of the giant entourages for the dozen hip-hop acts amassed for the Power 105’s DJ Prostyle’s celebrity birthday bash Monday night. Wale, Fabolous, Waka Flocka Flame, French Montana and others took to the stage for an epic concert. But the artists all brought giant entourages, causing a bottleneck at the entrance to the backstage area — and a ramp to collapse. One observer said the staging buckled after “12 dudes that weighed 300 pounds each and an extra 100 pounds for all of their bling jewelry” were on the ramp leading backstage. Sources say more than 400 people had packed in backstage, but it’s unclear if anyone was hurt. Hinting there could be some retribution, DJ Big Mike The Ruler tweeted, “The mini stage collapsed last nite at Hammerstein I know sumbodys neck hurts this morning. $$$$” The source added, “Those rappers need to be less co-dependent and only require 10 friends on stage — not 200.”