The concept of a "best friend for everyone in the world" is subjective and varies from person to person. Different individuals have different preferences, interests, and personalities, so what makes a best friend for one person might not be the same for another.
However, there is one entity that is often considered to be a potential "best friend" for many people worldwide: themselves. Developing a healthy and positive relationship with oneself can be crucial for overall well-being and happiness. Self-acceptance, self-compassion, and understanding one's own needs and emotions can lead to a stronger sense of self and improved relationships with others.
Ultimately, the idea of a "best friend" is a highly personal one, and it is entirely up to each individual to determine who holds that role in their life. Some people may find their best friends in family members, romantic partners, or long-time friends, while others might cherish the bond they have with a pet or find solace in their own company. The diversity of human experiences makes it impossible to pinpoint a single "best friend" for everyone in the world.