A list of reasons why many people believe Justin Trudeau has been a successful Prime Minister of Canada:

1. Championing Diversity and Inclusiveness: Trudeau has been an outspoken advocate for diversity and inclusiveness, and has taken steps to promote these values in his policies and actions as Prime Minister.

2. Legalization of Marijuana: Trudeau legalized marijuana in 2018, making Canada the second country in the world to do so. This has been seen as a progressive step towards reducing the harm caused by the criminalization of drug use.

3. Climate Action: Trudeau has taken strong action on climate change, including implementing a national carbon pricing scheme, investing in clean energy, and committing to achieving net-zero emissions by 2050.

4. Advocating for Women's Rights: Trudeau has been a strong advocate for women's rights and gender equality, including taking steps to address pay disparity and promoting women's participation in the workplace.

5. Support for LGBTQ2+ Community: Trudeau has been a strong supporter of the LGBTQ2+ community, including passing legislation to protect their rights and advocating for equal treatment under the law.

6. Strong Economic Growth: During Trudeau's tenure as Prime Minister, Canada has seen strong economic growth, including low unemployment rates and a thriving tech sector.

7. Building Strong Relationships with Indigenous Peoples: Trudeau has taken steps to build stronger relationships with Indigenous peoples in Canada, including increasing funding for Indigenous-led initiatives and working to address the ongoing impact of colonization.

8. Improving Canada's Global Standing: Trudeau has worked to improve Canada's global standing, including building strong relationships with other world leaders and promoting Canadian values on the world stage.

9. Investing in Infrastructure: Trudeau has invested in infrastructure projects across Canada, including public transit, affordable housing, and renewable energy.

10. Fostering a Positive Political Culture: Trudeau has worked to foster a positive political culture, promoting civility and collaboration, and encouraging constructive dialogue between political opponents.

These are some of the reasons why many people believe Justin Trudeau has been an effective Prime Minister of Canada.