Out of a economical curiosity I wounder at which point would it be more economical to scrape the web for wallet.dat`s and than spend the time and processor power to brute force the password instead of using the time and processor to mine BTC.
This would be the turning point for the hashrate and obviousely the value of the BTC.
Sad but true
Don't know what you mean by "scraping" the web, but wallet.dat files are not accessible on the public internet. You usually have to hack into someone's system in order to steal a wallet. Or you have to be a corrupt employee of a cloud storage/ web hosting service.
This has already happened several times, but it is becoming more difficult even for talented hackers, as the bitcoin community is becoming smarter about security.
Brute forcing the password will not work with the original Bitcoin client, unless the victim uses an embarrassingly weak password such as "1234". The client uses multiple rounds of hashing in order to make brute force attacks expensive.
Yes, for a handful of highly skilled black hat hackers it will always be more economical to steal wallets from careless bitcoin users, rather than doing honest work. But the majority of miners possess neither the skill nor the criminal energy to make their money this way.
