Why would you waste 3 dollars to buy this ?

[crazYgeeK]

Hi, I can understand what this sentence means, but I don't know which tense is used in this case.
Can I replace "Why would you waste 3 dollars to buy this?"
by "Why did you waste 3 dollars to buy this?" or anything else ?
Please let me know the differences between them. Thank you very much !

[emsr2d2]

Hi, I can understand what this sentence means, but I don't know which tense is used in this case.
Can I replace "Why would you waste 3 dollars to buy this?"
by "Why did you waste 3 dollars to buy this?" or anything else ?
Please let me know the differences between them. Thank you very much !

"Why did you..." means that the person you are speaking to already bought the thing for $3.

However, although you can ask "Why would you..." to a person who has already bought it, you could also ask it as a general, almost rhetorical, question. If you ask it that way, the "you" replaces "anyone".

You might see an advert for something completely useless or bizarre, which is priced at $3 and you may think or say, incredulously "Why would you (anyone) waste $3 on that?"