No.
If you're talking about pumping cash into our defense industry, the whole point is that's taking production away from elsewhere. Defense is getting bigger, something else is getting smaller in the short term.
Sure, the whole thing has some some ancillary benefits, like getting real-world data, or "advertising to prospective arms buyers", but those benefits don't make up anywhere near what we're spending. If we only wanted those benefits, we would get them far cheaper by themselves.
So no, there are absolutely downsides. This is the very broken glass fallacy that I referred to. I'll repeat the final paragraph of the original for you to read -- you may want to read the whole Wikipedia article though:
> It is not seen that as our shopkeeper has spent six francs upon one thing, he cannot spend them upon another. It is not seen that if he had not had a window to replace, he would, perhaps, have replaced his old shoes, or added another book to his library. In short, he would have employed his six francs in some way, which this accident has prevented.
https://en.wikipedia.org/wiki/Parable_of_the_broken_window
Again -- I totally support what we're doing, for the record. But money doesn't come free. We shouldn't pretend like this is all almost for free or something. It's not.