It's not necessarily incompatible, I just find it counterproductive at this stage. We're sending money to other people to help them, while people here struggle. Maybe if less people were struggling here we'd be in a better position to help elsewhere, and actually offer more help than we are now?
I don't think scale or magnitude come into it. There's always going to be someone somewhere in the world worse off than you, does that mean you should be forever aiding them regardless of the effect on you? Also, how do you decide who to help and who not to help? Who's 'worthy' of your help and who isn't?
Political choice is probably part of it, but that doesn't change the fact money that could be spent here is being spent elsewhere.
Politics is also about optics. Financially aiding or helping to arm countries that are assets/allies to us is logical - we get something back for what we put in. 'Humanitarian' aid is one of those things where it's a financial/political decision made on emotion, but also optics - it's a good look. Imagine if the Gov announced they were stopping all foreign aid?
Also, as I've said, t's not that I 'don't give a f**k', we just prioritise different things!