The Big Lebowski has a very specific style of humor and if you don't appreciate it for that, then there's not really anything left lol. The plot meanders around aimlessly as a joke and then the film just ends abruptly with almost no real satisfying resolution.
I think that was actually the point of that movie. Like the only time he actually tries to do any detective work, it turns out to just be a sketch of a dude with a comically large boner.
I kinda thought the disjointed nature was part of it, sending him through different social strata. Maybe I've watched it too many times while zooted, idk.