Is it impossible? Or is it because our poor millitary couldn't spare $2Bil to execute on these ideas? Or the global military budget by all countries couldn't

Is it impossible? Or is it because our poor millitary couldn't spare $2Bil to execute on these ideas? Or the global military budget by all countries couldn't spare $20bil to execute? I think it's very important to distinguish which things are technically not possible, vs we simply chose that our murder machines are more useful in the short term.