Earlier in the article: "“I want you to know how risky this is,” the son told his parents [in 1995, when they invested $245,573], “because I want to come home at dinner for Thanksgiving and I don’t want you to be mad at me.”"
"If they haven’t sold or donated anything else, the pair would own about 16.6 million shares, or 3.4 percent of the firm, making them the second-biggest individual owners after their son.A Hidden Amazon Fortune: Bezos' Parents Could Be Worth Billions (Bloomberg)
Their total return in that case would be about 12,000,000 percent, a performance that would make even the most celebrated venture capitalists blush. SoftBank’s $20 million bet on Alibaba has returned about 720,000 percent since 2000, according to calculations by Bloomberg. Sequoia Capital’s WhatsApp investment returned roughly 36,000 percent by the time Facebook Inc. bought the messaging service for $22 billion in 2014."