Well yeah, I know that having more than 10K in cash on you at one time is probable cause for "suspicious activities",
"Suspicious activities" isn't a crime, so it would be impossible for PC to exist for that. PC by definition means an officer believes there is evidence a crime probably happened. PC must exist for an arrest to be made or property to be seized.
I think you mean to say having $10,000 is cause for Reasonable Articulable Suspicion. A cop can detain for a "Reasonable" amount of time if he has RAS, but can not make an arrest or seize property based on RAS alone.