How many years of this not happening will you wait to go by before you would accept that you were wrong?
Here's my prediction. On literally every time frame (2 years, 5 years, 10 years, 20 years, 30 years, etc.), the government will:
1. Not produce any crafts built by NHI
2. Not state that they have recovered any crafts built by NHI*
3. Not produce any alien bodies
4. Not state that they have contacted any alien beings
5. Never produce any hard evidence of crafts doing anything that manmade crafts cannot do.
6. Will not produce any clear video of a craft that is not manmade (and confirmed not to be AI-generated video)
7. Will not produce any multi-source proof (such as video + radar, infrared + radar, etc.) of a craft that is doing something manmade craft can't do
8. Not announce the definitive existence of ETs or any other NHI that have visited Earth.
* This excludes, of course, any future craft built by AI that we ourselves have designed.
There remains the remote possibility that aliens will contact us at some point in the future, and thus my prediction would be technically wrong. But I find it extremely unlikely that this would happen in my lifetime when there's no meaningful evidence that it has happened in thousands of years of human civilization, and when the distances between us and them are so insurmountable. And I am virtually certain (99.99% or higher) that it has not happened already, based on what I know of physics in addition to what I know of human governments and human nature.