In his Office Hours, Professor Strominger mentions that two features of black holes — 1) the fact that we can never observe the inside (while staying outside) and 2) the curious relationship between Bekenstein-Hawking entropy and surface area — lend credence to the idea that black hole interiors may not actually exist and are better understood as holographic illusions. What do you think is the connection between being able to observe something and saying that it exists?
To exist means there is location and there is time. Inside the Black Hole BH space-time may have a very complex structure than outside the BH and these inside structures could perhaps be modeled mathematically. Perhaps here time is running backward since everything moves towards the centre with velocities greater than the velocity of light, However since nothing escapes a BH we cannot observe this structure. And so we will never know. This shows that observation is less stronger than existence. The existence may be there but it may not be observable. Whatever we observe however has to exists.
The large number of states coming from the connection of entropy of the BH with number of states, may have its origin in the projection of inner space to the surface of event horizon. But all this is beyond my imagination. Fact is the BHs exist and these have interiors