Bill Gates told the BBC he does not think traveling to Mars is a good use of money.
The Bill & Melinda Gates Foundation, the nonprofit founded by Gates and his ex-wife Melinda French-Gates, has put billions of dollars towards researching, developing, and delivering vaccines to the world's poorest countries.
Last year, Musk made a $5.7 billion charitable donation in Tesla shares to the Musk Foundation, which he launched with his brother, Kimball Musk, in 2002.
Gates and Musk have publicly disagreed in the past, including on COVID-19, how to address climate change, and space travel.
Musk and the Bill & Melinda Gates Foundation did not immediately respond to Insider's request for comment.