Your payment provider's automatic conversion is most likely more predatory than my bank's so I don't want to use it.
And even if you guess my location right, how do you know I want a badly/machine translated web site?
Why not let germans select iDeal and dutch users Giropay? They'll not click it if it's not useful for them. Adjusting the sort for what's most commonly used makes sense, but why actively thwart users from paying by geolocking payment methods by IP address...
Charging customers from countries with higher average purchasing power more and hiding the fact behind "charging people in the local currency for convenience" is much more profitable!
When price is set to $9.99 which works out to 47.89287237634 in your local currency. Although it would work out to 45.89327782 if you used your bank's conversion instead of the "helpful" service.
In those cases i don't think the seller makes any extra money, they get their $9.99 minus payment processor's fees. They just think they're helpful but make you spend more for no good reason.
As of a few days ago, Stripe is forcing all their partners to offer their customers the predatory currency conversion. There is no way to opt out, except switching to another payment provider with their own problems.
Billing address is not a sure way to predict currency.