Why is data stored on a NAND chip irretrievable if cracked?
All I want to get are some awesome holiday pictures back.


Lets be frank. They are not worth $1M to you are they. For that sort of money you could go on that holiday again a few times and recapture the same photos or something equally awesome.


  I would have thought some talented person somewhere would be able to patch up the area of the chip


The technologies used to manufacture flash memory do not lend themselves to repairing cracked ICs. The manufacturing approach is to simply test and discard defective dies. There is no established technology capable of making repairs. 

A silicon fab capable of manufacturing ICs costs $1bn. Any plant capable of repairing ICs is likely to be similarly expensive - it would need high volume usage to be economical. There just isn't that demand, most people probably find it cheaper and easier to copy photos onto a few $50 hard disks than to hope for sci-fi movie tech to rescue them.

Your talented person might need millions of dollars worth of equipment, a university-grade set of research labs, a large team of postgraduates and years or decades of funding.


  and get some of the data back.


Some of the data may still be present in undamaged parts of the chip but conventional retrieval is likely to be completely dependent on damaged portions.


  We're talking about a 256mb sd card here.


Imagine examining 2,000,000,000 individual grains of sand one at a time under a microscope. That's the scale of task involved. Grains of sand are much bigger than transistors of course. Transistors on flash-memory chips are far too small to see. 


  in a few years do you reckon the price of such an advanced retrieval could come down?


In a few hundred years?


  Should I just bite the bullet and give up?


Unless you are a billionaire with nothing much else to do who can fit this into some kind of bigger plan.