How do you prove that God exist?
How do you prove aliens are real?
Even is you discover a proof of those things, what would constitute an irrefutable proof? If you take a photo or a video of a real UFO, people will say it’s a trick.
Your job, competences or background might also hinder your proof. If you are a professional photographer or graphic designer and you present a photo as proof of a miracle from God, or an Alien invasion, people will discredit it.
If you have a criminal background or have been caught lying, people will assume the proof is not real.
With the raise of technology power and ease, proofs will be harder to come by.