Peter singers answers to the question how he justifies any kind of consumption that goes beyond the very basics "I am not a saint". He donates ~35%. However, he does not provide a moral principle or reasoning apart from "I am not perfect". For someone who is striving towards ideals, this is not very satisfying.
What is the moral foundation/ thoughts that you apply for not donating more?
Some may argue that consumption is very important since it provides jobs and in the end wealth that can be distributed (wealth that is distributed has to be generated before). Others may emphasize that they deserve more since they did the work.
What is your take?
I think pressure towards rationalizing one's self-interest as somehow being "optimal" is not a good idea. It's better to be honest.
Singer's answer is correct. It really would be better to give more. We don't because we aren't perfect. And that's fine! Cf. My response to Caplan's Conscience Objection to Utilitarianism.