About to start IB and wish I wasn’t

I’ve been a lurker on this forum for years and it is, in part, the reason I ended up in finance. I transferred from a shit school to a target one to make recruiting easier. I got the IB internship. Internship secured, I began obsessing over PE recruiting. I mapped out a future involving mega-funds and an MBA and then maybe a stint at a hedge fund. I did the internship. I got the return offer. Soon I’ll be starting this coveted job people are so eager to break into. 
At every step of my life so far, my decision making was primarily driven by two factors: prestige and pay. Nothing more. 

Perhaps this is why I now find myself looking towards my future like it’s a prison sentence. This job, that I chose for all the wrong reasons, is one that I cannot stand.

I don’t want to be ungrateful. I know I won’t regret getting some work experience. I know I’m lucky to have a lucrative job at such a young age, especially when a lot of my peers are struggling to find work right now. I know things will be alright in the long-term if I work hard. 

Right now though, all I feel is completely and utterly lost. 

I’ve got this pit in my stomach, the dread of going to the office, the dread of doing the work itself, which I just don’t like. I thought I could force myself to like finance, and that prestige and money would be enough to mask that nagging feeling that something isn’t right. But it isn’t. I don’t give a damn about either anymore. I’m about to spend 70+ hours a week slaving away at something I’m utterly uninterested in, all to earn these “benefits” (pay, exit to PE, “clout”) that no longer hold any value for me.

I don’t care about PE. I don’t know why the hell I ever wanted to work at a hedge fund. Oh wait, I do: it’s because I thought it would sound prestigious and smart. I’ve realized I never wanted to work in IB, I just wanted to be able to say that I worked in IB. Because when you have no idea what the hell you actually want to do, it makes sense to just do the thing that sounds the best, the thing that everyone regards as exceptional (even though it’s really not all that.)

I’m sad because I don’t want to do this, and then I’m angry at myself for not wanting it. I got everything I spent years planning for and still feel like I’ve failed. Discovering that I don’t want to work in this industry feels like a deep personal failure, like a weakness of character. Especially since I don’t know what it is that I do want. I feel so old and so young all at the same time. Most of all, I feel foolish.

If you made it this far thanks for reading my rant. If you already work in the industry, how long would you suggest I work this job before changing roles? Is eight months long enough to avoid damaging my resume? Or should I not quit at all and just tough it out, do my 2+2 and then switch tracks?