The difference between a mad person and a writer who creats fiction is, that we can define a clear line between imagination and reality.
You can write a book about alien spaceships and orcs but the moment you think it is all real. you will be marked as crazy by the soceity. I think this is a clear concept for everyone.

But this is only because we all can agree on what is real and what is not. We all accept a common ground, where we start. To be a bit philosophical: we accept a point as objecitve if all subjectiove viewpoint accepts it as such.
If someone do not accept, then we consider that person crazy. If more than one person choose to refute the same, then the majority, who does will consider them outsiders. And if the number of persons, who is against the majority goes over a treshold, they are considered to be on a diferent opinion.
Now comes the difficult part. We consider something to be true if it can be derived from an objecitve point with objective steps. But with evolution came higher level of thinking goving birth to abstract toughts. These things have no substance that can be measured or directly observed; their validity is the result of the objective steps called reasoning. If the reasoning does not contain contradicting stepts and points then it is rational but if any of the steps or points are not objective then it will be considered irrational. And as the level of humanity’s thinking progressed, we created abstract toughts which are derived from other abstracts accepted as objective truths. (By the way, irrational is not a curse word.)

And therein lies the problem.

If you are labeled as crazy, how can you change that stigma?
Your first option would be to accept the same things to be an objective truth as the others do. Your second option is raising the number of people who share the same opinion as you do. Doing so constantly, you will go from crazy to outsider to someone who have a different opinion. And if the trend does not stops, then your point of view will be considered as an objective truth. This is what we call progress.
But the problem lies with abstract toughts. If you can convince enough people of your subjective views, then the meaning and nature of these thoughts will change as well. Like what we consider to be dirty or beutiful. And at this point the problem pops up. Because the change is gradual and at one point all your reasoning will be objective but contradictory at the same time, making it neither rational or irrational. And if you instead of adjusting the discrepancies, choose to ignore them and call your reasoning rational, I feel obligated to call you out on that.

So this is what I mean, when I talk about the world is turning crazy. And do not worry. I will follow up with examples.