The government's job is not to maximize its ROI. For example, (and I make no argument about whether the current situation does this), protecting its citizens is of extreme moral importance, even if it's very very expensive and unlikely to somehow feed back into the economy in a way that recoups the cost long term.

99% of school lunches have zero ROI. Parents can provide them just fine.

Everyone except the president is suggesting this will turn into a regional forever war.