Questions like this always depend on how one defines friend and best friend. People have different perceptions and opinions. It is really up to the individual.
Coming from the military it was tough to have a "best friend" as every few years we all rotated to another assignment or even location. I suppose that these days, with social media, it is easier to keep track of people than it used to be.
Now, as an old fart, all my colleagues have their lives and families so it is once again difficult to cultivate a "best friend". But then I have a more conservative definition of friend and consider someone lucky if they have 2-3 good friends in their lifetime. Others have a more liberal definition. What ever works for people.
So, in order to try and identify common ground -- what exactly IS a best friend and what makes them different from a friend?