Is it a good idea for a 1st Yr IBD Analyst to live alone in NYC?

Think it’s fine. You’ll rarely be home and most often when you are you’ll want quiet / solitude. As long as you already have friends in the city you’ll be fine, the worst part about living alone is not always having a roommate (roommate’s friends) to hangout with 

Dude nothing wrong with living alone...if anything I would say that's better. 100k base will be fine. I'd say 2.5k max. Enjoy yourself. It's not like you are blowing your money at the club or something. Comfort is important.

In NYC the number to qualify for rent is 40x base salary (since your bonus is not in writing/confirmable) so $2.5k is your absolute max.

If you are someone who really enjoys having your own space, go for it. Especially these days when everyone is in/out of the office so much and you're likely to spend at least some time working from home.

My only caution to you is how insane the market is right now - $2.5k doesn't go very far at all and will probably be a very very small, walkup studio without a full kitchen and no laundry in unit or building, so have to deal with laundromats. That's really the main reason why people choose to have roommates - they spend the same or a little lower amount for a liveable place. But if you're okay with a much smaller space in exchange for it being your own, that's totally fine.

I got a studio for $1750 in the UWS last month that's very livable. Able to have a kitchen, living space, eating area, workspace, and bed in a loft. You can find great apartments in your price range if you look in the right places.