Often in these situations, there are a few reasons. Monetization of users isn't always as good as the MAU would make it seem, or those users have significant overlap with Snap and don't represent a net gain to the company. This is especially true if acquisitions are more of a defensive measure (buy a business so someone else can't gain access to the users you already have).

Finally, sometimes in a bad market a business can be worth more as a write-off than a sale. Depending on Snap's balance sheet, they may get more money back in tax breaks than they would if they sold it (and, again, giving a competitor access to users you already have).

This is all hypothetical, of course. I don't know anything about this specific situation, but it's why lots of seemingly successful products get killed.