You’re allowed to have an opinion. In fact, you should have an opinion about everything.
But don’t confuse opinion with facts. Just because you think something is real doesn’t make it so; look for evidence, have an open mind, and be willing to change.
Earth is not flat no matter how firm is your conviction; there’s plenty of empirical evidence for it. And if you cling on to this, you’re not opinionated; you’re ignorant.
The truth is sometimes difficult to discern and unravel, but more often than not, statements someone boldly makes on the internet can be easily verified with a bit of digging.
If you’re looking for a conspiracy, you will find one. The same goes for the truth.