I have a feeling if it ever reaches that point, the thieves would know enough to take a break and spend their cash. And then after some period when the national alerts have cooled down, they would resume their activities. If the thieves were smart, they would not spend that money frivolously and invest intelligently so that they would be set for life, and not have to continue with these increasingly riskier nighttime ventures.
Don't banks keep track of the serial numbers of the bills put in their ATMs? They could track the serials to their so called investments and WAM! Caught red handed!