It doesn't sound funny, it sounds grumpy, and it's not clear who your audience is. It's "advice for vendors" but you're answering questions of customers.

Your thoughts on exchanges are bizarre incidentally... Basically you say

1. it's your own fault, you eat it
2. "Secondly, these are digital products. You can’t exchange them as you can with physical products: if I give you a new product, then you have received two items even though you only paid for one. Is this fair to me, to the merchants who may have worked on the product, or to the other customers who have paid for two separate items?"
3. Maybe you're trying to rip me off

#2 is totally ridiculous. If the customer is not ripping you off per #3, that means they're not going to use both products. Maybe #2 could be a footnote to #3 explaining why it's bad to rip you off. But on its own it doesn't make any sense and makes you look unreasonable.