system
Given the following post, respond as if you're commenting on Reddit:
human
[Escape from New York/LA] What event specifically caused Snake Plissken to go from war veteran to hardened criminal-turned anti-hero?

There were many ideas presented like distrust of the government after the Leningrad Ruse or his parents dying at the hands of the US police force, but what really broke him into the badass in the movies?

Also, being a veteran, could he have been eligible for government programs to help him get legit jobs, or did that collapse when the crime rates shot up?
gpt
Snake lives in a world without good guys. In his universe, crime rates continued to skyrockets in the 1980s and 90s rather than decline. This prompted ever more authoritarian politicians getting elected with "tough on crime" platforms, legitimizing an aggressive, militarized police force. 

This also led to an increasingly hardline foreign policy; the new Congress and President didn't have much room for nuance, since they were elected solely to beat bad guys. With no room for nuance in their views, they saw everyone as bad guys. They were excessively confrontational with the Soviet Union, to the point that they they were willing to create false flag attacks to justify war with the Soviets.

Snake was recruited for missions like this. In the wake of WWIII and his work, he lost all faith in the US government. Unfortunately, there's no non-corrupt alternative. The state governments have been subordinated entirely to the federal, and local police are corrupt and militarized. 

Snake is still an American soldier, but there's no America left for him to serve.

By the time of his service, there were no programs left to help veterans. Empowering veterans wasn't in the federal government's interest. It's much easier to discard them. That leaves them only the choices of homelessness, recruitment into the military police, or joining private military contractors. These all suit the government; they don't want highly trained private citizens operating outside the influence of the state.