That's my point. OP reduced the effectivenes of psychedelics down to just being able to feel good for a short while.
Well do some cocaine and you'd feel great for about an hour but nobody cured their depression that way.
I take your point, but I think the distinction is that some drugs can make you feel euphoric, but psychedelics affect you on a deeper, psychological level. You're not just feeling an absence of pain or a rush of pleasure (though that can happen, too), you're also thinking in a different mindset.
On high dose psychedelic, “you” are not thinking in a different mindset. The current “you” is completely obliterated. This is the difference between psychedelics and other drugs.