How much ground beef is needed for 130 people?

It depends on what are you making, and who is eating.

I live in a family with ten kids and for tacos we use about 3-5 pounds of meat per meal and get about two tacos give or take a couple people, so for 130 people you would need somewhere between 39 and 65 pounds of meat for tacos.

If you are making burgers, and they are say a quarter pound, and you want everyone to be able to have two, then you need a half-pound per person, so 65 pounds. 130 pounds if you are going to make thick half-pound burgers, or you are feeding a bunch of football teams, or people who might graze on three or four quarter pound burgers over the length of a long picnic. :)