Why not sooner than later?

One thing i keep hearing when it comes to disclose is humanity is not ready because of the ontological shock.

We know the concept of space, we have been exposed to many movies based on aliens, so we know the concept of aliens. So many people that I have talked to are open to the possibility that there might be life out there somewhere in the universe.

So, why do the government believe that humanity will go into ontological shock? (Is it just a farce so that they can hoard the technology for money and power?) And for a moment let’s assume that we might go into the shock, does that mean the government should never let the humanity know that we are not alone?

We as a human species are very good at adapting to the situation, so do they really believe we can not come out stronger after knowing the truth?