Arms dealers benefit the most. As the government backed by those weapons, America gains coercive influence in the world, so that’s a secondary factor.
The arms dealers have it particularly good though. They get to sell a lot of highly profitable weapons. They get to test all of their new weapons in combat. And best of all for them, if their weapons inflict a large number of civilian casualties, nobody really cares. With the data they gather from killing a lot of Palestinians, these arms dealers can make a really effective presentation to their next despotic dictator. If they aren’t sure whether a particular munition will cause a lot of civilian casualties in urban area, they can test it in Gaza. If it kills too many people, they will know for next time that it’s OK to use that weapon against black and brown people but it won’t be as acceptable when white people are involved. Also useful information for a dictator who wants to terrorize his population.