is it necessary to come out to the world

[hank]

That boyhood friend seems very... prejudiced.
Having pre-conceived ideas on bisexuals that, from how you put it, sounds like you weren't too keen on, and telling you how you should act.
But perhaps i'm just reading it as more forceful than it actually played out.

No, you don't have to be out to everybody, nor make it a priority to tell people you're bisexual.

You can if you want to; but all in all, it's just not necessary.

Its quite a common misconception that males cannot be bisexual, I get it from straight and gay guys alike, straight women too.

I think my friend said he was bi for a few years as a way to ease out of the closet. Nothing wrong with that, but just because he couldn't come bounding out straight to gay doesn't mean that's the case for every one.