Three strikes can be triggered with much less, even petty theft can trigger it. In this example, the defendant received 25 years in prison for his third crime of stealing a pair of socks[0]
"Specifically, the Three Strikes law made it possible for a repeat offender to receive a prison sentence of 25 years to life for a nonserious or nonviolent felony (for example, petty theft with a prior)"[1]