In 2002, Byrne took Overstock public. Early in his tenure he attracted public attention for a long-running legal battle against short sellers and "naked short selling." He eventually resigned as CEO in August 2019, following revelations that he had been in an intimate relationship with Russian spy, and future politician with Vladimir Putin's United Russia party, Maria Butina.
Byrne then emerged as a leading figure in promoting conspiracy theories, including the "Deep State" conspiracy theory. In 2020 and 2021, he repeatedly promoted claims that Donald Trump won the 2020 U.S. presidential election due to voter fraud.
He has also toured the United States in order to provide anti-vaccination stump speeches for COVID-19 conspiracy theorists. He became notable for distributing and selling misinformation on various subject matters via websites, social media, books, and film. He has also been noted for his conservative views on public education.
Byrne played an active role supporting efforts to question and push baseless claims about the 2020 election, including attending a meeting in mid-December at the White House to discuss strategies to overturn the election. That meeting with Trump also included former national security adviser Michael Flynn and his lawyer Sidney Powell,
It focused on ideas to block Joe Biden’s certification as president and discussed the prospect of seizing voting machines. White House officials in the meeting pushed back at the ideas in heated exchanges, CNN previously reported.