let's say I run a simple race attack (say in a restaurant). I transfer BTC to the restaurant but seconds before (or after) I send the very same coins to myself. To make this deal more likely for myself I assign a much higher fee to the transaction loop for myself. How common are such race attacks? I don't think the restaurant can wait like 6 blocks before they accept my payment. I would be most happy if you can point me to papers, stats, etc. Or is there a big gap in my logic?