There are perceptions and there are facts. This is true whether the facts are easily knowable or not, and extends as much to the existence of God and other such questions as it does to the sum of two numbers.
Do you dispute that facts are also perceptions?
"Whether it is actually giving insight or not (it could definitely be some idiosyncratic interaction that lsd is having with your brain to make you see things in a certain way); it's at the very least fun, and can have a drastic effect on the way you oritent yourself toward reality."
There is something seemingly objective about it though in that others seem to have very similar experiences.
Then there's the solipsist point of view, which is to say, it doesn't matter that someone else thinks you are deluding yourself, because all that is knowable is in your own mind, so you aren't capable of validating anything anyway.
Either way, the experience is validated, to one's self or to the world.
Do people bring back useful (in the engineering sense) knowledge from their times tripping/rolling? Are they more likely to experience e.g., fruitful insights akin to Kekulé's vision of the benzene ring as an ouroboros, as a result of having consumed these drugs? If so, then the drugs may indeed live up to the claims that they grant access to "truer and deeper" levels of reality. Otherwise, their users are simply fooling themselves. (Although fooling yourself can prove useful; the almost universal belief in deities among humans fulfills some sort of purpose, though it is my belief that that purpose is no longer relevant.)
It might feel like you are tapping into something truer and deeper, but that doesn't mean that you are.