"At 10 parts per quadrillion, the Earth's oceans would hold 15,000 tonnes of gold", says the Wikipedia page on gold.

I'm inclined to think we've lost that gold.

Practically speaking, sure. It's obviously not cost-effective to extract it. But it's there if someone can get it. I don't expect anyone to be extracting gold from ocean water, but there are other source of other elements that may not be cost-effective now but could be in the future or may simply become necessary despite the cost.

Effort high enough to consider that material lost to any practical purpose like a tv.

Cost scales with refinement effort, so it just results in more expensive TVs. That said, pretty sure we'll have drowned the planet in landfilled TVs long before this becomes a serious issue

If prices of certain metals were high enough I bet people would stop throwing out TVs and dig up old ones from the dump.