The problem is that you are using two very contradictory arguments. You can’t claim that there is limitless unknown on earth, to support claims of people spotting BigFoot. If people are there claiming to see it, then the area isn’t the unknown of limitless potential.
That’s because you need to explain what those unexplored areas are. Once that picture is painted, you will see that sighting accounts simply don’t match up. We are not discussing depth of oceans, or frozen Antarctica, or even deep undiscovered wilderness... we are talking about people camping, usually within 100 miles of large populated cities.
The most obvious evidence they don’t actually exist, is your phone camera. It’s illogical that pictures of big foot have not increased, as everyone has cameras at arms reach. The idea you wouldn’t or couldn’t take a picture, is less likely than it ever was.
Yet, another big problem for crypto zoology in general, is climate change. We have animals moving further south, as food becomes depleted. In the same sense, the big foot, would likely need to make the same track closer to populations, due to food shortages. Big foot would likely have a different biology, that is unlike other large mammals of the area, if their reaction to lacking a food source, is different.