I disagree. USAID is involved in a lot of stuff and most Americans probably have no idea what they do. Here are a few points to consider:
1) They're mainly involved in humanitarian efforts.
2) Their annual budget is around $40bn, which is .7% of the fed budget.
3) Some people think that military and economic "sticks" are our only tools for influencing foreign countries, but USAID, along with diplomacy, are key elements of "soft power". Things like dealing with problems over there before they become problems over here.
4) There are multiple levels of oversight and strings attached to the aid we send, both before and after we send it.
A big chunk of the aid has gone to Ukraine in the past few years for obvious reasons. We do this both because they're an ally of the US and because we have strategic interests in the region.
This is a fairly easy read:
https://www.cfr.org/article/what-usaid-and-why-it-risk