Long story short I bought my car for 25k 5 years ago and they gave me 13.5k now.

You received more than 50% of your purchase price for a 5 year old car? You only got scammed if the KBB value was significantly higher.

I see my car up for sale at a dealership much later up for 18k.

Yes, always grossly haggle a used car's price when you're shopping around.

If you can confirm that this is indeed your car then you can consider offering the dealer $5k for it but be prepared to be denied since they know they can get much more in the current market especially if they fixed the cosmetic issues.

If you think your car was good enough to drive then you could have talked to your insurance to deduct the salvage price from the payout. I know more than one person that has done this.

This seems to be main salt in your wound since you were not aware that you can do this.

Long story short I bought my car for 25k 5 years ago and they gave me 13.5k now.

You received more than 50% of your purchase price for a 5 year old car? You only got scammed if the KBB value was significantly higher.

I see my car up for sale at a dealership much later up for 18k.

Yes, always grossly haggle a used car's price when you're shopping around.

If you can confirm that this is indeed your car then you can consider offering the dealer $5k for it but be prepared to be denied since they know they can get much more in the current market especially if they fixed the cosmetic issues.

If you think your car was good enough to drive then you could have talked to your insurance to deduct the salvage price from the payout and keep your vehicle. I know more than one person that has done this.

This seems to be main salt in your wound since you were not aware that you can do this.