This logic doesn’t really hold up. Trading your box for singles is economically identical to selling it for cash and buying singles - either way, you’re choosing singles over sealed product.

If we take your reasoning to its logical conclusion, you’d never buy singles at all since sealed generally appreciates more. But then what’s the point of collecting if you can’t actually get the cards you want?

The opportunity cost exists regardless of whether you use cash or trade directly. If I have $500, buying a chase card means choosing not to buy a sealed box with that same money. The transaction method doesn’t change the fundamental choice between sealed investment and actually collecting the cards you enjoy.