You also need to account for the odds that the hard drive even contained the claimed BTC, and that it remains recoverable, even if found.

If you could somehow guarantee that there is a hard drive with a recoverable $765M on it in that landfill, that would be a very different scenario.

The article says that it was known at the time to be likely to be within a 2000m^2 block, narrowing beyond that will be harder since the rubbish is distributed across it (bulldozers keeping it somewhat level as dumping proceeds, rather than keeping it date-sorted). At the time that he first understood his loss the prospective value was $7.5 million: far from negligible but not a slam-dunk proposition for sifting through 10,000 tonnes of mixed bulk waste while continuing to operate the landfill.