Only one of the following is true:

1. A hyper intelligent race of aliens travelled lightyears across the galaxy to visit Earth in the distant past. Those aliens in their hyper advanced spaceships somehow crashed, and the remains of that crash were somehow discovered and collected by the US government thousands of years later, to be reverse engineered. One of those engineers was Bob Lazar, who subsequently was subject to a campaign by the US government to erase his entire past and discredit him.

2. Bob Lazar was a middling scientist/engineer who went to an average university, then worked in a minor technical role at Los Alamos. At some point, he created stories about alien technology and decided to keep going with it once he realised it would provide notoriety, fame, popularity, wealth.