Word-geekery alert
Good old English.
Consider -ard (or, occasionally, -art)*, what the Online Etymological Dictionary refers to as a “suffix of derogation.” Attached to an adjective or verb, it denotes someone who carries said action or quality to excess.
A bastard is base-born.
A braggart brags too much.
Before it became associated with a particular kind of bird, buzzard was a term for a species of raptor considered not good enough to hawk with.
A coward is easily cowed.
Though dastard now means “cad”, the word originally denoted an excessively stupid person, someone who was dazed.
A drunkard drinks (or is drunk) too much.
Stinkard needs no explanation.
Which brings us, of course, to wizard.