Let us see. A celibate man wearing a hairshirt, living in the desert in perpetual fast, -- is he doing something or is he having himself a mind change?
John the Baptist was a sinner just like all born of Adam, including Mary.
The repentance John the Baptist came preaching was repentance of the false religion of the Pharisees and 1st century Judaism which, like Roman Catholicism was of works righteousness, empty rituals, legalism and "sacraments", and to come to true faith in Christ, the Messiah, a message that Rome needs to hear as well.
Point remains, he was doing something to give example of repentance.