Theories on UFO activity since the 50s

Hey folks. I’ve recently been reading an old book, “The Truth about Unidentified Flying Objects” by Coral Lorenzen. It has great info and sightings from the 50s. It seems in the late 40s, 50s and 60s (possibly longer?), UFOs were interacting really close with people.

They were sighted very near the ground, on the ground (like the Zamora incident), and were even spotted with figures in or around them.

Those types eventually fell off by the 70s I believe. In the book, they theorize that after the atomic bombs were tested, that triggered the visitation, and UFOs began mapping our planet and even collecting samples of plant life, etc.

That theory does make sense to me. Now, if we go with that, what would have made them stop and pull back? There are very few sightings like those on recent decades. Possibly they just got what info they needed and that’s it.

Or possibly we were able to get our hands on one that either crashed or was brought down. That would align with the fact that we seem to have developed some very advanced tech i.e. Black triangles which I believe are most likely human tech.

The book got me thinking and I decided to post so apologies for this not being well thought out or coherent haha.

But I’m interested in what others opinions are.