They say: only the fittest of the fittest shall survive, stay alive!

The fittest survive. What is meant by the fittest? Not the strongest; not the cleverest — Weakness and stupidity everywhere survive. There is no way of determining fitness except in that a thing does survive. "Fitness," then, is only another name for "survival." Darwinism: That survivors survive.

It cannot but happen that those individuals whose functions are most out of equilibrium with the modified aggregate of external forces, will be those to die; and that those will survive whose functions happen to be most nearly in equilibrium with the modified aggregate of external forces. But this survival of the fittest, implies multiplication of the fittest. Out of the fittest thus multiplied, there will, as before, be an overthrowing of the moving equilibrium wherever it presents the least opposing force to the new incident force.

only the strongest we survive

The trouble with words like "fit" in these discussions is that, if taken in a wide sense they are liable to become vacuous, and if taken more narrowly they easily become tendentious. Thus the phrase "survival of the fittest" does not mean much if it means only "survival of those most likely to survive." If on the hand it means "survival of those whom we should admire most" or the like, it describes a different state of affairs; we shall need different arguments to persuade us that this is happening. In just the same way, Wilson equivocates with the notion that to be "fit" is an advantage to anybody. If it means "healthy" or "able to do what he wants to do" then it usually is so. But if it only means "likely to have many descendants," then there is no reason for treating it as an advantage at all.

If evolution was worth its salt, it should've evolved something better than "survival of the fittest." I think a better idea would be "survival of the wittiest." At least, that way, creatures that didn't survive could've died laughing.

People who think of themselves as tough-minded and realistic, among them influential political leaders and businessmen as well as go-getters and hustlers of smaller caliber, tend to take it for granted that human nature is selfish and that life is a struggle in which only the fittest may survive. According to this philosophy, the basic law by which man must live, in spite of his surface veneer of civilization, is the law of the jungle. The "fittest" are those who can bring to the struggle superior force, superior cunning, and superior ruthlessness.

The expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient.

The weak die out and the strong will survive, and will live on forever

According to Darwin’s Origin of Species, it is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust to the changing environment in which it finds itself.

He who can handle the quickest rate of change survives

In my lifelong study of the scores of species of ants to be found in the tropical forests of Dal Hon, I am led to the conviction that all forms of life are engaged in a struggle to survive, and that within each species there exists a range of natural but variable proclivities, of physical condition and of behaviour, which in turn weighs for or against in the battle to survive and procreate. Further, it is my suspicion that in the act of procreation, such traits are passed on. By extension, one can see that ill traits reduce the likelihood of both survival and procreation. On the basis of these notions, I wish to propose to my fellow scholars at this noble gathering a law of survival that pertains to all forms of life. But before I do so, I must add one more caveat, drawn from the undeniable behavioural characteristics of, in my instance of speciality, ants. To whit, success of one form of life more often than not initiates devastating population collapse among competitors, and indeed, sometimes outright extinction. And that such annihilation of rivals may in fact be a defining feature of success.
Thus, my colleagues, I wish to propose a mode of operation among all forms of life, which I humbly call-in my four-volume treatise-‘The Betrayal of the Fittest’.

Obsessional Scrolls
Sixth Day Proceedings
Address Of Skavat Gill
Unta, Malazan Empire, 1097 Burn's Sleep

“The law of evolution is that the strongest survives.”
“Yes, and the strongest, in the existence of any social species, are those who are most social. In human terms, most ethical.”

Darwin’s notion of the survival of the fittest was a key element both in the Marxist concept of class warfare and of the racial philosophies which shaped Hitlerism.