You need to hit big and assemble a team. Watch Masterminds on Court TV channel. Most get caught !
The common hold-up man may get a few k, but needs to repeat regularly, thus his demise, like a punter that over-bets.
Randomness helps in crime. If you could murder some random person and collect millions for your effort, it would be easy enough to do so and get away with it ..once, if you could accept your actions as being legitimate, or not care !
Petty bank robbery may suceed even 10 times in a row, but never big enough !
Disclaimer: I never robbed anyone, never would !