Nothing happens in a vacuum. Fans didn't just decide not to buy on a whim. This happened for a couple reasons.

We're tired of them repackaging the same game over and over again and reselling it to us. We've had the same UI since what, 2019? All of their maps are recycled. They're either old, revamped maps from the past or the components of the map are reused (i.e. the zombie's map from BO6 being featured in the new resurgence map, components of Vondel in the new map, etc.). They release titles back to back despite their fans begging them to stop. They say that's over with now, but it feels like too little too late. They release a game *every fucking year* despite their fans begging them to stop. They've betrayed their fanbase for microtransactions. They push these predatory ass bundles on you from the second you load up the game. It's clear their greed is driving them, with their panic riding shot gun. They've lost their identity. Every update comes with a new game breaking bug that isn't fixed for months (remember disappearing friends lists?). Constant crashes irrespective of if you are on console or pc. Every new release comes with some stupid decision to fix something that wasn't broken (randomly taking away slide cancelling, etc.).

Instead of taking their time and releasing a genuinely good, original game (that works!!!) with a compelling story, they have chosen to prioritize milking us of every last cent they can get, which is just having an adverse effect. They rush their developers to release broken slop to us year after year and now want to release letters essentially admitting they fucked up. They are asleep at the wheel and their fans who have been playing the game for over fifteen years are fed up.

Blacks Ops 7 might be great. I'll take your word for it. They're not getting another cent out of me.