Whether or not that's true depends upon what you're looking for by way of evidence.
Well something measurable, demonstrable, repeatable, etc. Some sort of scientifically credible explanation for where things like 'spirits' are supposed to exist, what type of matter they are comprised of, why they can seemingly materialise and dematerialise to suit whether the human at hand is amenable to suggestion or not, why the presence or otherwise of 'spirits' appears to be completely random and haphazard and not dependent on circumstance, cause and effect etc. I'm not talking about pseudo-scientific garbage explanations like 'the afterlife', 'psionic manifestations', 'ether', 'traumatic events', I mean proof to the sort of standard that we require to believe any other sort of claim made about the existence/reality of other things.
The burden of proof doesn't lie with the sceptic, it lies with the people who claim these things are fact. Fine, they might argue that they feel no need to demonstrate to sceptics that they are indeed real, but I find it more telling that whenever that challenge has been laid down, including with substantial rewards for the challenge being met, it's singularly failed to produce any sort satisfactory response.
For people who are insistent that their homes are 'haunted', or that they are sharing their homes with 'spirits', surely, even to put an end to sceptical mocking, you'd be happy for the world to examine your claim and produce tangible evidence to show that you are not completely barking, yet nope, not a single case of undeniable proof attained.
There's a lot of testimony, and many people who do believe in ghosts/paranormal don't consider it possible to simply write all of it off as lies or misunderstandings.
Whether believers consider it possible or not is neither here nor there. The fact is, nobody has provided anything that bears up to scrutiny that could be said to be cast-iron proof that there is any such thing as a 'ghost', 'spirit', etc etc
There are also photos and videos. It hasn't been possible for sceptics to debunk them all. I don't know which ones may be real - I'm not an expert - but when people who apparently are experts say that they can't work out how some of those photos/videos might have been faked I'm interested to hear it
Again, burden of proof does not lie with 'debunkers'. There's no need to debunk every single photo or video, because sceptics are not trying to prove the existence of anything. That onus lies with the people making the claim that these things are real. Just because the explanation for how a specific video or photograph came about isn't immediately to hand says absolutely nothing about the existence of 'ghosts'. It does not mandate the existence of the paranormal, it's just a video or a photograph that appears to show something out of the ordinary.
To be honest, with the number of posters in this thread claiming to have witnessed ghosts, paranormal events, etc, the world must be absolutely teeming with such things, yet still nobody comes forward with anything that stands up to scrutiny. The sort of explanations they provide are on a par with some of the complete nonsense that religious believers spout. "Oh, ghosts only appear to those who are amenable/susceptible". I mean, come on... we're all the same species, we're all remarkably similar. Sure, there are differences from individual to individual in quality of sight, hearing, strength, size etc, but it's not like some people are born with an extra sensory organ that can pick up signals 'from the other side' and some of us are not. That's laughable nonsense. The 'other side' of what for starters? Again, another layer of pseudo-scientific nonsense used to 'explain' things that don't require an explanation in the first place.