suicide snails?

I am always wondering why snails climb up on walls, on fences, on trees even on the top of plants.

What do they want there?
There is nothing to eat, no moss, no algae, no water.
And it is also no good protection from enemies.

And there are very many, everywhere.
Here I can still imagine that they have lost in the search for food.

But here?
Are the bunchy jumping snails waiting for the rope?
Or suicide snails?
Or are they too stupid to creep straight ?

I do not know and the snails tell me nothing. Do you have an idea?