> Compare that with gold, or any other asset.

Depends on what you're trying to do of course. If you're looking to physically send gold somewhere, you're spot on.

I can buy and sell GLD at a zero transaction cost. I can buy $100,000 of GLD at zero transaction cost, then sell it, then repeat that a hundred times.

What will Coinbase charge for the same thing in Bitcoin for $10 million worth of transactions?

I can also store that virtual gold purchase at a low cost indefinitely (GLD has a 0.4% annual fee that it extracts; IAU is 0.25%). After you account for fees, that is likely to compare well with using a service like Coinbase to store your Bitcoin.