It happens sometimes in human history - though parallels may be dangerous - that when the natural road towards human fulfillment is blocked, human beings retreat into themselves, become involved in themselves and try to create inwardly that world, which some evil fate has denied them externally. This is certainly what happened in Ancient Greece when Alexander the Great began to destroy the city-states, and the Stoics and the Epicureans began to preach a new morality of personal salivation which took the form of saying that politics was unimportant, civil life was unimportant, all the great ideals held up by Pericles and by Demosthenes, by Plato and by Aristotle, were trivial and as nothing before the imperative need for personal individual salvation.
This was a very grand form of sour grapes. If you cannot obtain from the world that which you really desire, you must teach yourself not to want it. If you cannot get what you want, you must teach yourself to want what you can get. This is a very frequent form of spiritual retreat in depth, into a kind of inner citadel, in which you try to lock yourself up against all the fearful ills of the world. ... You gradually hedge yourself round with a kind of tight wall by which you seek to reduce your vulnerable surface - you want to be as little wounded as possible. Isaiah Berlin, The Roots of Romanticism.
I can certainly accept the economic and political conditions of the Hellenistic period contributed to the development of Stoicism but it did flourish throughout the affluent Roman Empire until the rise of Christianity. Sour grapes is a little harsh but Stoic philosophers did warn against forming attachments to transitory material goods and people(!!). However they didn't object to obtaining these goods in the first place.