WTF? Nobody says scientists know everything. Engineering and Science go hand in hand. The better your technology is, the more you can do with it. How scientists’ theories get tested is greatly limited by our technology. We need brilliant minds to imagine the possibilities and then bring them to life. There isn’t even just one type of physicist or an engineer you know.
As for why we haven’t discovered a particle since 1931, every advancement in technology and scientific calculations count and there has been progress though you fail to see it. Also, it isn’t exactly like coming up with a new iphone. We are talking about things we cannot see or touch. If scientists start making false claims like you know who then we got a problem. The discoveries heavily depend on our technology but the technology would be no where without scientists. If you knew anything about the history of Science, you would know the gap between discoveries is huge. You say physicists have others thinking that they know everything yet YOU ARE THE ONE expecting them to tell you everything. Why the expectation? Like I said earlier, Science isn’t comforting. Stick to Philosophy and religion to soothe your soul.