Promoting US interests isn't "donating".

Some of the spending probably does fit that description, but I bet if we had a truth oracle that could actually tell us, it would be a lot less than you think.

The 'other people' agree to it, via the democratic process. It's not stolen money.

You're going to feel really weird when, in response to the US's waning engagement with global geopolitics, a bunch of countries form trade organizations and jettison their dollar holdings. Kinda like how a bunch of dairy and grain farmers felt when they realized the "welfare" programs they loved to bitch about were actually poorly camouflaged agricultural subsidies. Whoops.

All taxes are theft then?

We live in a polity. That polity can be generous, well-regarded, respected, feared, and despised. The admixture of those attitudes affects our polity’s ability to pursue its interests.

(I also happen to think that our polity should assist the least fortunate on its own merits, but you may not)

I already do