Not discrediting you, but can we get a source for any of those declarations?

Aegis and SM-3 seem to be working for some forms of missile defense, including some BMDs.

It's a hard problem space and a lot of the apparent success/failure is really a matter of choices and tradeoffs made by the 'customers' who specify the design constraints.

Aegis + Aegis Ashore definitely seems to have potential. Assuming a Nork threat you would want to intercept mid-trajectory if you could, and that means pre-positioning your platform in the mid-Pacific. If you are intercepting on the terminal phase then things are pretty desperate...

THAAD doesn't work? I actually thought it had been largely a success.

I read somewhere it has a ~50% success rate. So it seems if the logic is this simple, it works, you just need to launch 3 missiles at the target to be confident about getting an intercept.

According to a comment elsewhere on this page, the PAC-3 interceptor has a 19/22 (= 86%) success rate in tests. But in the article we are commenting on right now, they fired 5 interceptors at the target, and apparently all of them missed! The article hints that the issue might have been that the system misclassified the targets and hit the booster instead of the warhead.

The moral is that you can't be sure that the success rate is independent, there can be systematic errors that affect all of the interceptors at the same time.

You mean some internet blog told you it had a 50% success rate?

The actual tests are 100% successful. Do some basic research please. https://en.wikipedia.org/wiki/Terminal_High_Altitude_Area_De...