My take on the reason animals with a ‘self’ evolved.
The “self” is an type of “virtual storage device” which allows for complex social rules to be transmitted outside of direct DNA transmission.
The advantage gained by the creature from the transmission and storage of complex social information is the ability for “lamarkian” evolution; that is adaption within a generation, even within a single lifetime of the way the animal behaves. This allows for both efficient genetic transmission of essential traits, and efficient adaption of the group as a collective. The big payoff for the animal is via highly complex society, intelligence is exponentially rewarded. Any advance in technology can be transmitted socially in ever increasing sophistication and complexity. Which, increases the generational genetic selection of more intelligent members of the group.
In short, the ‘self’ is the incubator for intelligence.
The question as actualism, and the answer, is the incubator is no longer required. Indeed, is now limiting the advance and advantage of intelligence.
So there are now roughly 3 groups of organisms on earth;
Purely DNA based behaviour.( Bacterial, plant/most invertebrates)
DNA/Self/Intelligence based behaviour (some invertebrates, some mammals, humans )
DNA/Intelligence based behaviour (actual freedom).