It's not bullshit though, for Hume didn't say the sun wouldn't rise. He said it
might not. Such a possibility is perfectly coherent with a world in which the sunrises every single day!
Hume never denies there can be a world which always follows the same rule. If that's what the world does, then that's what happens. Just because anything and everything else is
possible, it doesn't mean it happens.
Under Hume, the definition of what the world does moves from the
idea (e.g. the rule which constrains possible to form what happens), to the world itself. The sun
can always rise tomorrow, but it takes the
existence of that state every morning, not a rule. Rules become expression of existing states (i.e. the behaviour of states), rather than constraints which limit what states could be-- even as the sun rises every morning, any other state was possible. Actuality doesn't undo the truth of possibility.
Conjunction doesn't need to be constant at all. In terms of a cause, it only needs to happen once. Let's I find this object. It's the only one of its kind. If I pick it up it will be destroyed and l result in the death of all life on Earth. Is there no causal relationship here? Well, no. There is one. If I refuse to pick up this object, the death of all life on Earth will be avoided.
"Rules" tend a little be different. In the above instance, for example, the rule of killing all life on Earth is only relevant for one brief moment. Unless, that relationship
repeats in future times, there is no danger to picking up the object. While there is a "rule" to any instance of a cause, we don't talk about them in this sense because then we wouldn't have any use for them going forward.
So for our usual notion of causal "rules," we need
repetition-- e.g. I know I will be alive tomorrow, and the sun will rise, so I can do X,Y,Z, plan my day, respond to how the world repeatedly affect me, etc.
We tend to confuse this repetition of conjunction with a constant. Instead of realising that the rules are only how the world is behaving at the moment, that it's a repetition which might never have been and could end in the next moment, we think they must necessitate what happens.
It's ourselves which are the primary concern here-- if a conjunction is constant, then we can't be wrong, the world will always turn out how we expect and, perhaps most importantly, we won't be dead. I mean just imagine what it would mean if we could just "pop" out of existence tomorrow: I might be dead and would have no way of preventing it!!
The desperation to deny radical contingency, to claim it doesn't make sense with a meaningful existence, is our pretence that we are not the sort of thing which could just cease tomorrow, which might be wiped out on whim. In saying, "But the sun MUST rise tomorrow," we really are telling ourselves the lie that we cannot die, that we are beyond the possibility of death or non-existence. We are simply too afraid to accept we might not be (which is quite silly when you think about it, for that one
might not exist, does not mean that one will).
"What are the chances?" is an entirely irreverent notion in this context. Since radical contingency deals in
logical possibility, rather than probability, there is no defined chance to anything. Possibility isn't causal. There is no means or standard to define what's going to happen or what's more likely to happen.
In fact, considering the world itself, we might say there is no chance at all. For given the casual states themselves, the is only one outcome: what exists. If we ask, for example, "Why does the sun rise rather than not. How come it the rules of the world didn't change to day?," there is no answer. That's just what happened. There is no chance
this sun would do anything else, even though it could have.