Wilson Fisk, also known as Kingpin, got out of prison due to a combination of narrative developments across the Marvel series timeline and some in-universe legal and plot explanations:

• At the end of Daredevil Season 3, Fisk is sent to prison after his crimes are exposed. He agrees to keep Matt Murdock's identity secret in exchange for Vanessa Fisk's freedom, and a promise that he won't harm Karen Page or Foggy Nelson

• However, Fisk later reappears as a free man in the Hawkeye series. It is explained that after the power vacuum created by Thanos's snap (the event known as "The Blip"), Fisk was released from prison. This event disrupted normal law enforcement and political order, allowing Fisk to get out

• Fisk never returned to prison even after the Avengers reversed the snap in Avengers: Endgame , as confirmed by his appearances in Echo and Daredevil: Born Again

• In Daredevil: Born Again , Fisk not only remains free but also successfully runs for and becomes the Mayor of New York City. His ability to run for office despite being a convicted felon is explained by New York election laws, which only permanently bar individuals from running if they were convicted while holding office. Since Fisk was convicted before considering the mayoral position, he was legally allowed to run

In summary, Fisk's release was facilitated by the chaos following Thanos's snap, which created a power vacuum. The MCU has not shown a detailed legal process for his release, leaving it somewhat ambiguous, but the storyline incorporates this event as the key reason for his freedom and subsequent political rise