Why do believers thank god for every good in this world?

it offends me that an invisible god is given credit for every good thing that happens in this world, while evil is blamed on humanity. there is much evil that isn't the fault of humans such as ignorance, disease, and droughts. most things that are good are products of human love, effort or genius. (like vaccines and irrigation pipes). a god could do so much good in this world like warn innocent children from danger or turing weapons into flowers (that would be a "miracle" for you.) so when a doctor saves a life we should truly owe our thanks to a doctor and society making their education possible. it is insulting to both when "god" is thanked for something that he could have done himself but didn't. if a loving god really existed, we would not need doctors in a first place...