The question is: "What is a fact?"
Generally speaking, something like Gravity is a fact. If I step off of a cliff, I will fall (probably to my death). It would be quite the exception to the understood rules if someone were to step off of a cliff and not immediately begin falling as the law of gravity says they should. It's possible there is some exception to gravity out there that we have yet to find or stumble upon, but barring such an exception, it is an understood fact that an object released without support will fall to the ground. We call this "Gravity" - but that is actually stretching the fact beyond our ability to describe it, as there are many theories as to what force(s) produce the law of gravity.
Different people have different standards for what they consider to be a "fact." Some would consider the measured diameter of the Milky Way Galaxy to be a fact. I would argue it is an estimate based on several theories that postulate the lights in the sky are other stars and that our methods of measuring the distance to them is accurate. This sliding scale of what people consider facts determines, generally, their world view. There are many things, taken as 'established fact' by many in the world of academia, which I contest are mere theory, often supported by little more than institutional dogma.
Because of this, it is proper to say that, within the discussion of mostly academic subjects - such as theories and debates where little experimentation can be done, then people are entitled to their own facts. They are allowed to believe Gravity is a fundamental force produced by gravitons or higgs bosons. Whatever helps them sleep at night. However, they are not entitled to believing that they can simply step off of a cliff without falling because the law of gravity doesn't apply to them. Since most subjects exist in the middle of these two extremes, people have a very subjective view of what is and is not a factually-based viewpoint.
Until such a point as the mechanisms of the universe can smite us for our held views, we are 'entitled' to our own understanding of what is and is not a fact. Of course, this enters a whole new world of problems when the discussion is trying to determine what is and isn't a fact about human society and behavior... when those facts are then used to create policy and deprive people of freedom, life, and property....