John Hume has been breeding rhinos since 1993 and owns the world's largest rhino farm in South Africa.
He fought a global ban on trading rhino horn, which would allow him to sell it to pay for his farm.
For a minimum of $10 million, you can buy 2,000 white rhinos in South Africa.
For years, he campaigned to make it legal to sell rhino horn — a substance more valuable than elephant ivory, cocaine, or gold.
Without being able to sell rhino horn, the cost of running his ranch — including his sophisticated security system consisting of radar detection, helicopter patrols, and armed guards — finally became too much.