There are only 170,000 tonnes of gold in the world. Is that a fatal flaw in gold since it is not possible to own 1 tonne per person?

Scarcity exists. It will always exist. Picking any unit and saying "There aren't enough of these for everyone to have one" is arbitrary.

Bitcoin is fungible to eight places and even after that can be patched to support more.

What is the difference between everyone having 1 bitcoin and everyone having .003 bitcoin? Nothing.