Yes it is.

Some opinions are shared by very many people. But how does it make them more worthy? Can you be sure something is right just because a lot of people think so?

People are led by their opinions. Sometimes somebody's opinion is not accepted. Often that is not justified, for example if it's about private affairs. Other times, people do not seem to see any problem in saying that somebody's point of view is just wrong. That is the case if he speaks for murdering or running around nakedly in public areas.

Of course, we all know both is completely wrong. :-|

If you think long enough about it, you can question anything.

It's sick.

No, it isn't.

I meant, there is no facts (nor spoon).

Of course, you know the sun is hot. But everything you know is just the interpretation of your mind from the input it gets, but is there even something like your mind?

I cannot even be sure that I'm really writing this here, heck do I even exist? Is the concept of existance senible, is there something like a world?

Logical thinking nullifies any "facts". Everything is based on assumptions that work well with how most people understand the world. In physics, there are only theories...

However, how can you be sure your thinking works correct? Do you even "think"?

"And of course: Crouching Tiger, Momento, A Beautiful Mind, Monsters Inc, Matrix, etc ... "

I have never seen such a diverse list followed by "etc.."