There is a special place in Hell for those who post a screenshots of text instead of links to the source and text.

However I found that document - https://www3.weforum.org/docs/WEF_GlobalRisks_Report_2013.pdf

There is no mention of exact reason of why discovery of alien life is a risk at all.

What is stated:

Over the long term the psychological and philosophical implications of the discovery could be profound. If lifeforms (even fossilized lifeforms) are found in our own solar system, for example, it will tell us that the origin of life is ‘easy’ – that anyplace in the universe life can emerge, it will emerge. It will suggest that life is as natural and as ubiquitous a part of the universe as stars and galaxies are. The discovery of even simple life would fuel speculation about the existence of other intelligent beings and challenge many assumptions which underpin human philosophy and religion.

How that is a risk at all? There is no any assumptions in any religion about alien life at all.

But however, they want do the following.

Through basic education and awareness campaigns the general public can achieve a higher science and space literacy and cognitive resilience that would prepare them and prevent undesired social consequences of such a profound discovery and paradigm shift concerning mankind’s position in the universe.

What "social consequences" they want to prevent? I posted an answer earlier: https://conspiracies.win/p/11RO7SpyUw/theory-why-they-keep-aliens-them/

It's easy. If aliens exists, there should be civilisations that are superior to our. And that directly means, that our authorities, including tptb are not highest authority in the universe. Also, there inevitably comes a potential possibility to escape that earth authorities control for an earth individual. That is completely inadmissible for earth powers.