About $12.86 billion, Kynan Eng, a computer scientist based in Zurich, calculates.
Eng, who by day is the president of iniLabs, a Zurich-based company that focuses on brain research and computers, with a side interest in using virtual reality as a rehabilitation tool, found the amount as a result of answering questions on Quora.
He came to Quora to respond to questions about the intersection between neuroscience and human-computer interaction but then "fairly quickly found myself getting diverted answering silly questions," he said from Switzerland, according to CNBC.
One of his first answers was about how much money was spent rescuing Matt Damon in all his various movies.
The total came out to $900 billion "plus change," he wrote.
That included $100,000 for the search party in Saving Private Ryan, $100 million for space station security deployment and damages in Elysium and $200 billion for the Mars mission and rescue in The Martian.
He's also come up with a name for his new hobby.
"I call it 'amateur fictional economics,'" he said.