For a lot of these bored street kids baiting plod and initiating the chase complete with evading the chopper crew is an extension of a computer game.
There is no intention from the start of stealing the car to sell on.
They often work out a chase route and escape path. As for evading thermal imaging just dump the car in a city centre and walk in to a supermarket, bus station or pub and job done.
The cost/risk analysis does not make sense.
For those who get caught and feature in those police camera action tv shows it's a badge of honour. We've all seen Smokey and the Bandit.
The other aspect of this type of policing is the distraction theory where plod is wasting time on petty crime while real villains are making money.