"Whatever, I don't care," Fiers said, according to Susan Slusser of the San Francisco Chronicle. "I've dealt with a lot of death threats before. It's just another thing on my plate."
The 34-year-old also isn't concerned about playing in Houston during the 2020 campaign.
"If I'm worried about any retaliation, I'm not going to be ready for the season," he said.
The Athletics and Major League Baseball are aware of the threats and are taking measures to protect him and his family, Slusser reports.
Fiers said Wednesday he can defend himself after commissioner Rob Manfred stated the league is concerned about the player's safety.
The nine-year veteran added he has no plans to return his World Series ring unless the rest of the 2017 team does the same, according to Slusser. That sentiment is apparently causing a stir among Astros fans.
"I said from the beginning, 'I'm not away from this. I was part of that team, I was one of those guys,'" Fiers said. "Suspensions, fines - I'm willing to take as much punishment as they do. If they ask me to (return the ring), it's not the end of the world."
Oakland contacted the league before Fiers went public to complain about the Astros' cheating. However, a subsequent investigation was reportedly inconclusive as players wouldn't cooperate.