Why are Green Turtles endangered?

Mostly because they can dry up in the hot sun, predators ( sharks) humans, and pollution.

They are endangered because people want the shells, flesh, and leather from the turtle. They use the shell to make hair combs, cosmetic holders, fancy plates ext. They use the leather to make purses and bags. People eat the flesh, its a delicacy in some places.

Answer2: Sea turtles have been harvested for their meat, which is considered a delicacy, and for their shells, which are collector's items.
The Green Sea Turtle is endangered mostly because they are accidentally caught by fishermen in nets that are meant for fish or are caught up in pollution, such as plastic bags. The green sea turtle loves to each jellyfish and sometime mistake a plastic bag for food. As of coarse they cannot eat plastic bags they choke and unfortunately die. They also eat things such as bottle caps etc. There are also a lot of people who dig up the turtle nests even though it is illegal. This puts the eggs at high risk of dieing as they are berried to keep a certain temperature and when they are dug up the incubation process in ruined and they become cold and die.

Answer2: Sea turtles have been harvested for their meat, which is considered a delicacy, and for their shells, which are collector's items.
Green Sea Turtles are endangered because of accidental by-catch (caught in nets meant to catch fishes), water pollution (indirectly), turtle consumption (some 'people' still eat them or their eggs, which really is just ignorant), real estate development reduces nesting areas, predation on land by crabs and voracious seabirds of various type, and predation in the sea by Tiger sharks.

Not ALL greens are endangered. In Hawaii they have made a wonderful comeback and have been delisted to threatened. There is much discussion about taking them off that list as well as the population there continues to grow steadily. Around the world all sea turtles are IN danger of becoming by-catch, and polluted water affecting the seaweed, swallowing fish hooks, getting caught in unattended nets, fishing lines, and drift nets. Other troubles such as being struck by boats (their hearing is not the greatest), and even being intentionally taken are included. As far as natural predation by tiger sharks (and others), tiger shark JUVENILES (under 13 feet) consume greens at the rate of 17%, with other animals such as fish and carrion being most of their diet. Natural predation not a problem, but man made is. (reefannie)
The first cause to it becoming endangered is man-made waste tossed into the oceans as well as cruise ships tossing garbage bags out their shoots. The worse is the six-pack plastic holders that come from the cans. It is usually a slow and tourmented death, of suffercation. Fishing lines, hooks, and abandon fishing nets would be the next cause to their extinction. Then comes the case of people building homes and condos closer to the existing beaches that turtles are known to return to. These turtles return yearly to the same place that they were born. Polution is another factor, as we put more chemical into our storm drains that contaminate our ocean. We have also fished out most of our bays and oceans, as well as the the fisherys that net for fish and drown the turtles. tossing them back in because they have died or on the verge of dying. The list goes on!