Depends on your definition of "overwhelming" 1 in 5 convicts are in prison for drug related offenses[1]. Almost four hundred thousand US citizens behind bars for plant byproduct possession or distribution is heinous. There are around 320k prisoners for property crime, by comparison, so no, nonviolent drug offenses are #2 in terms of incarceration blocks, though the numbers are close, and violent offenses are over twice drug offenses.
Ranked, reasons for incarcerations go:
1. Violent crime
2. Property crime
3. Everything else
Where "violent crime" is comprised of those crimes we all agree are violent --- particularly: domestic violence, which accounts for a plurality of all incarcerations in major metro areas.
The overwhelming majority of incarcerated felons victimized somebody else. It's also worth considering that the majority of those incarcerated for property crimes victimized those people in society least able to absorb the harm: rich white people live in low-crime neighborhoods with 2x the police coverage.