overestimating
o-ver-es-ti-mat-ing
verb
Judging something or someone's value or ability as higher than reality.
"He was overestimating his chances of winning."
Thesaurus
Synonyms: overvalue, overestimate, overappraisal, overvaluation, overestimation, overrate, overreckoning, overrating
Antonyms: underestimate, underrate, undervalue