Trade in old Apple Watch

According to Apple Trade In:

1. Trade-in values will vary based on the condition, year, and configuration of your eligible trade-in device. Not all devices are eligible for credit. You must be at least 18 years old to be eligible to trade in for credit or for an Apple Gift Card. Trade-in value may be applied toward qualifying new device purchase, or added to an Apple Gift Card. Actual value awarded is based on receipt of a qualifying device matching the description provided when estimate was made. Sales tax may be assessed on full value of a new device purchase. In-store trade-in requires presentation of a valid photo ID (local law may require saving this information). Offer may not be available in all stores, and may vary between in-store and online trade-in. Some stores may have additional requirements. Apple or its trade-in partners reserve the right to refuse or limit quantity of any trade-in transaction for any reason. More details are available from Apple’s trade-in partner for trade-in and recycling of eligible devices. Restrictions and limitations may apply.

Why is the trade in value so ridiculously low? I just bought my Apple Watch series 8 on June 10th (3 months ago) and the trade in value is only $180 when I paid nearly $500 + full coverage Apple Care.

If you're not happy with what Apple is willing to offer you, you should consider selling it privately.