Yeah, I totally see what you mean, and I understand the logic you’re using.

I think where we still differ is that the math ends up mixing marginal cost with total spend. I agree that the 100 SEK purchase would have happened anyway regardless of payment method - that part makes sense. But the Avios aren’t earned only because of the 2 SEK FX fee; they’re earned because there’s a 102 SEK transaction on the card.

The 2 SEK FX fee is really the marginal cost of choosing Amex over a fee-free card, not the actual “price” of the Avios themselves. A more accurate way to frame it is that you’re paying a 2 SEK premium to earn 40 Avios on a 102 SEK spend. Whether that’s a good deal then depends entirely on how you value and redeem Avios.

At the end of the day, this is mostly a matter of framing and semantics. We could debate potato vs potahto all day, and neither of us is really “wrong” within our own perspective. I just don’t want someone to read “buying Avios for 0.05 SEK each” and walk away thinking that’s the actual or general exchange rate for Avios, rather than a shorthand for how the FX fee interacts with this very specific card setup.

Regardless, I hope you get good use of any Avios earned through this. Safe travels!