Can someone please explain the "waifu tax" to me?

Whenever I see any discussion about maliss someone inevitably mentions how it's gonna cost a waifuillion dollars due to the "waifu tax".

So i decided to look other DBP with waifus like valiant smashers and sure the centur-ion cards are more exepnsive than average, but isn't that because they are a decent option in the meta and the other 2 options in the pack being vaalmonica and memento not that much? Also being in the 5 ur slot dosen't help.

I'm relatively new so I don't have the knowledge as to how expensive these cards were when they were released.

Whenever I see any discussion about maliss someone inevitably mentions how it's gonna cost a waifuillion dollars due to the "waifu tax".

So i decided to look other DBP with waifus like valiant smashers and sure the centur-ion cards are more exepnsive than average, but isn't that because they are a decent option in the meta and the other 2 options in the pack being vaalmonica and memento not that much? Also being in the 5 ur slot dosen't help.

I'm relatively new so I don't have the knowledge as to how expensive these cards were when they were released.