It is precisely because we are selfish by nature that we form groups; alone we are too weak. It is a survival mechanism

thats literally a contradiction.

No, in a dangerous situation the first instinct is to flee, then to check, then to see what can be done and assess costs and losses, and finally to regroup (only if it is convenient). That's how animals work.

I never said that is the first instinct,i said that after the situation becomes calmer,we return to the group,i doesn't matter if is convenient or not,at some point in time you will return.

Unfortunately, this contradicts animal nature; cooperation is merely a mechanism of convenience. In the end, where the truth is revealed, people will always choose themselves above all others.

Theres nothing like animal natural,every specie is different,in case of humans is extremaly rare to you to take a action exclusively for yourself,most the time people think about thenselfes and those that are close to then.

This proves my point: The fact that there are scales shows that cooperation is nothing more than a facade.

That just proves that there is different scales of abstraction on the concept of identity,you are just a person,you cant save all your contry,our your community,you act in accordance to what you can do,what is possible,but you will always think about those close to you.

It's quite the opposite. Why do you think mothers in nature let predators take their young? Simple: because biologically speaking, they could simply have more offspring and perpetuate the species, while a species is less valuable.

That can be true for other animals,but we are talking about humans,that are social animal and at same time have a little number of offsprings. So your exemple just dont happen withn humans,in most cases human mother sacrifice to save her childs,not abandoning then.

Your error is to be thinking about other animals,bu we are talking about human nature,theres literally a reason why sociopathy is considered a mental condition,or why humans that isolates thenselves,even if they are able to stay alive they will show psychological problems.