Malala Yousafzai, the Pakistani teenage education activist who survived a near-fatal attack by the Taliban and subsequently gained international attention for her support of women’s rights, has become a millionaire in less than four years thanks to sales of her memoir and appearances on the global speaking circuit.

Yousafzai, 18, the youngest person to win the Nobel Peace Prize, skyrocketed to international fame after she emerged from an assassination attempt on a school bus in Pakistan’s Swat Valley on October 9, 2012. That day, a gunman asked for her by name, pointed a pistol at her, and fired three shots. One bullet hit the left said of her forehead and went into her shoulder. For days after the attack, Yousafzai remained unconscious in critical condition.

Her condition improved enough for her to be sent to Queen Elizabeth Hospital for medical treatment in Britain, where she has since remained. She has since been in constant demand globally. In 2013, United Nations Special Envoy Gordon Brown launched a UN petition in Yousafzai’s name, demanding that all children worldwide be in school by the end of 2015. A German newspaper dubbed Yousafzai “the most famous teenager in the world,” and Time named her as one of “The 100 Most Influential People in the World” in 2013, 2014, and 2015.

Each of her speeches, as reported by The Japan Times, have been in high demand worldwide and cost about $152,000. By comparison, the South African social rights activist and former Anglican bishop Desmond Tutu reports collecting $85,000 for every speech. Yousafzai has delivered speeches at some of the world’s most prestigious universities, headlined international conferences, and conferred with world leaders to share her experiences, which were the subject of the Oscar-shortlisted 2015 documentary He Named Me Malala.

Her memoir, “I am Malala,” published in 2013, has sold almost 300,000 copies in Britain and, as reported by International Business Times, 1.8 million worldwide. The book has earned her over $3 million in sales. The Guardian called the book “fearless” and stated that “the haters and conspiracy theorists would do well to read this book.” Interestingly, the All Pakistan Private School’s Federation announced that the book would be banned in its 152,000 member institutions, claiming that it disrespected Islam and could have a “negative” influence on young people. A children’s edition of the memoir was published in 2014, and the audiobook edition narrated by Neela Vaswani won the 2015 Grammy Award for Best Children’s Album.

All of these activities have considerably enriched Yousafzai, who now commands the same kind of wealth as successful lawyers, financiers, and CEOs. In addition to her publishing activities and speech-making, Yousafzai launched in addition to The Malala Fund, an organization dedicated to supporting girls’ projects in developing countries, a family-owned company called Salarzai Ltd., in 2013 to protect the rights to Yousafzai’s story. The London-based company, owned by Yousafzai, her father, Ziauddin Yousafzai, and her mother, Toor Pekai, has a net worth of £1.87 million as of August 2015. Last year, Yousafzai’s family company turned over £1.1 million in taxes, and the teenager will have to pay £200,000 in tax money.

Some have criticized the ethics surrounding Yousafzai’s newly acquired fortune and have questioned her commitment to advancing the world’s less fortunate while profiting significantly off of such activities. A spokesperson for Malala, defending her lucrative activities, said:

“Since the publication of Malala’s book, Malala and her family have donated more than $1 million to charities, mostly for education-focused projects across the world including Pakistan.”

Yousafzai’s parents also defended the activities of their daughter.