Most U.S. foreign aid is credit to be spent with U.S. defense manufacturers. In other words, "foreign aid" is a way to hand out U.S. hardware to allies or those for whom it's an effective bribe. The best example of this is Egypt, which has enjoyed ~$3B annually in U.S. gear as the payoff for making and keeping peace with Israel since the Yom Kippur war in 1973.
I don't really consider money going from my pocket, to Egypt, then to the US military industrial complex as "staying in the US." My taxes should go to things that benefit me and other regular citizens, not war profiteers.
You definitely should question it. The US had the highest foreign aid budget in the world but little to show for it.
If you are an effective altruist and want foreign aid to benefit the world, you should be concerned that it's funnelled to defence contractors instead.
If you just think the US wastes too much money on it's military you should be concerned that they are sneaking more money to defence contractors under the guise of humanitarianism.
US citizens enjoy a lot of wealth that was extracted (sometimes very violently) from the rest of the world, and you could make the argument that maybe the US citizens should give something back to the people whose exploitation they enjoy.
But in this case "foreign aid" seems to mean mostly "weapons for dictators", so it doesn't look like a constructive use of the funds.
And how much of that $300 billion is actually just serving intelligence goals?