system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why didn't the Dursleys gladly ship Harry off to Hogwarts?

They hate him right, 9 months whitout harry per year most have been a dream.
gpt
They were so anti-magic that it actually overrode their desire to get rid of him.

After all, for Petunia, she had a lot of trauma tied up in magic.  She felt rejected that she wasn't invited to Hogwarts like her sister, and that resentment drove a rift between her and Lily that lasted the rest of their lives.  And was probably a factor in her marrying the most normal, uninteresting, non-magical guy she could find.  

To her, having Harry be a wizard was a constant reminder that she wasn't special, and likely a reminder of the time she lost with her sister.  And to Vernon, it was a reminder that the world wasn't simple and boring as he wanted it to be - not to mention the embarrassment of public incidents in front of his boring friends and family.  So they abused him his whole life, hoping to stamp the magic right out of him.