And shouldn't you be thankful that the spiders are still around to eat all the other poisonous crap you aussies have running around in your outback? At least while they're busy eating other stuff, they aren't eating you.
It doesnt work that way. The poisonous creatures tend not to have many predators, because any would-be predators get... y'know... poisoned. All the poisonous stuff just works together to ensure that there are no non-poisonous creatures left in australia.
Personally, Im going to have to either develop venomous fangs or shuffle off any day now. Thats just how it works.