Anyone who doesn't see the use in this card has never played the 5-Sanity investigators on Hard or Expert. Part of playing Mark Harrigan on high difficulties is being able to survive losing four Sanity in the mid game. Allies are great, but plenty of Guardians are limited to guardian allies which will only go so far. Roland Banks is in a slightly better place with his selection of throwaway allies, but is still very interested in this card. Guardians are ultimately fragile and more liable to die off mid-scenario than most other characters. Despite being the class most hard up for resources, cards like this can go a long way toward winning a campaign.
Something Worth Fighting For may be assigned horror dealt to other investigators at your location.
Something Worth Fighting For is a funky card. It's a relatively bad card, in that it highly inefficiently does just the one thing that loads of other cards do better. It negates a bit of horror at the cost of 3 resources, an action and a card. Compare this to, say, Beat Cop who gives you + or Art Student who picks up a clue or Dr. William T. Maleson who does 66% of Something Worth Fighting For's work at 33% of the cost AND has damage tank AND an ability.
In case its not obvious yet, the reason Something Worth Fighting For is still worth a card slot in rare few decks is this: All of those other cards are allies!!! Without access to Cherished Keepsake or Holy Rosary there's is a very real dearth of horror tank options that aren't allies and even those two are accessories, therefore occupying a different contested slot themselves (a problem that characters can attest to).
So, Something Worth Fighting For occupies the weird niche of preventing horror without filling any slots, more like a healing event (Logical Reasoning) than an asset. Certain characters will find Something Worth Fighting For occupying a key niche: Expand your horror tank without interfering with your allies.
Oh, there's also an ability text? Yeah you can just ignore that, you can bother to dig it up for the niche cases where a friend is literally 1 horror from death and you playing Something Worth Fighting For might help them reach the final clue or resignation location. 90% of the time, this is YOUR horror soak.
Finally, True Grit for sanity; exactly what Guardians have needed since the game released.
But just how good is it really? A deck slot is pretty valuable, and given the array of allies who can provide a similar amount of soak while also providing other effects (and being cheaper, sometimes), it might struggle to find a space. Its other issue is that your allies generally have more sanity but less health than you, so True Grit is still your best choice for the team.
That being said, I think Mark and Zoey are all about this card. They have the least access to high-sanity allies from other classes, so this in-faction soak is a godsend for them. Additionally, Roland could use it to shore up his beleaguered sanity, and Lola might want it for the same reason.