Do you have any tangible reason for that belief?
One of the main 'tangible' reason in my opinion is that i've had weird experiences. I can think of natural alternatives to explain them, but the natural explanations seem more far fetched than what i actually experienced. So, those opened my eyes up to experiences in general. So i've spent a lot of my life not only researching other peoples experiences but asking everyone i meet about if they've experienced anything bc i'm sorta obsessed with knowing i'm not the only one. It messes with your head bc if i was i would be worried about my mental state. But, at this point, i've ruled that out 1) bc my uncle is a neurologist and i've learned a lot about the mind and delusions; and 2) i'm not the only one. The way i look at it is out of the millions of people reporting experiences, only 1 of them has to be true for the implications to be wild. So, that is pretty crazy in and of itself. But i don't jump to conclusions. I don't know what could explain these. It could very well be something about consciousness that we aren't aware of and has very little to do with any afterlife or other dimension. So who knows what it means... but i'm quite confident they happen. So i think it is enough to suspect something is going on... one of those somethings is extra dimensions and higher consciousness. I believe we know too little at this point to rule these things out.
Also some reasoning, i don't think we've even begun to test for an afterlife or other dimensions. The closest we come to studying it is in a theoretical type of way like multiverse stuff. Science currently doesn't have any means to test for this stuff. Science is best suited to discover our reality not any transcendent reality. Factor that it, that we really haven't even tried yet nor have the means too, i think it's close minded not to suspect these things especially given how incredibly unbelievable life is in general. We've only begun to scratch the surface of existence and we are already blown away by multiple unbelievable facts about life... i don't see why something like life after death just wouldn't be another unbelievable reality.
My last reason is just personal. Ever since i can remember, quite literally from the age i can remember which is 4/5 and up, i've always felt like i was somewhere else before this life. Sorta like some young kids having past life memories, i felt like i had multiple experiences already. I remember as a kid imagining some pretty crazy stuff even before i've seen it and as soon as i was old enough to reason, i thought back and thought the things i've seen as a kid were impossible... and that's what initially got me interested in metaphysical subjects. Of course this one is really just a personal feeling and old memories... but they're significant to me nonetheless.
So all of that together, and of course other things like philosophy, metaphysical hypothesis, observations of this world and even science, i don't think it's too far fetched to suspect something like life after death. I truly doubt this is the only reality that has intelligent beings like humans that has 'ever' existed and in the doubt i can see some pretty crazy implications of our type of mind plus infinite.