What is the ruling on the frequent fantasies that a person has about heroism, fame, and the admiration of others? And are these considered self-talk, showing off, or something else?

Fleeting thoughts that pass through the heart without being sought or settling within it are not held against a Muslim. However, if one seeks out these thoughts, allows them to settle in the heart, and takes pleasure in them, and if they pertain to something forbidden, such as thinking about the charms of a non-mahram (definition) woman, then this is forbidden. Drowning oneself in trivial thoughts is blameworthy, and a Muslim should take care to guard their heart from indulging in vain thoughts that are of no benefit in this world or the Hereafter.