Sometimes more is more
Congrats! You're obviously somewhat familiar with the FIRE movement, which means you're already ahead of the game! Earning a high income can either facilitate reaching your goals more quickly, or make you feel that much more regret when you fall behind. So let's stick with the former!
Those of us making big money have a big opportunity. If you can live off $40k, you only need $1M to retire. I know "only $1M" sounds like a joke, but believe me, it's not. If you can stash away $100k a year when you make $200k a year between retirement accounts, investments, and savings, that's 10 years of work assuming you never get a raise.
Working with high income earners
This is where your challenge begins. Plenty of us are first generation high incomer earners. No one in my family under the age of 45 had ever made six figures before. I found myself with a $200k job at 25. Yet even with those humble beginnings, this world can really suck you into spending money on shit you didn't even know existed 6 months before your first day on the job.
Fancy coffee, rooftop lounges with $20 cocktails, custom suits, Gucci loafers, Frategonia vests, and Raybands. These are a few of my not favorite, but someone has told me to buy them things. Sometimes it feels like if you don't look like you belong in this world, it might boot you out early. Well spoilers: that's bullshit. Unless you're violating your job's dresscode, or appear to be wearing the wrong decade, saving money on that crap will help you attain the truly important things that much faster. For example, a few people on my floor walk in with a traditional Starbucks coffee every single morning. Normally, I wouldn't bash too hard on this, but we have a cafe in the office that BREWS STARBUCKS COFFEE and will give it to you for 99 cents if you bring your own container. Sorry, but that's just being irresponsible.
A new mindset
I've found being upfront about my lofty financial goals probably isn't the best route at work. Definitely don't go up to partners and brag about how you want to quit in 7 years because you won't waste money like him/her. As annoying as it is, until we hit our financial goals, we need these jobs, and having people like you and thinking you're part of the crowd is unfortunately a plus. However, demonstrating knowledge about taxes, 401k accounts, and benefits actually helps a lot. I've guided a few first-year associates in this and it actually makes you appear financially literate (because you are), and not frugal (even though you are).
The truth is 99% of your office can't tell the difference between your clearance rack clothes compared to a Thom Browne $5,000 suit (which, again, I didn't know existed until someone mentioned it and I actually looked it up). So unless your dream side gig career is modeling or fashion, look to save on shit you don't really care about.
I've found being a secret FIRE community member in biglaw to be pretty fun. You feel like you're living a double life, and watching your colleagues waste a golden opportunity can be somewhat exhilarating at times (if you don't like them I guess).
The truth is that for many of us, these high salaries won't last forever. Jobs like biglaw, finance, etc. are loaded with people who are truly passionate about this stuff and will undoubtedly be improving on their crafts for the next 40 years. I'd rather avoid a week of 2am nights in my 40s and be more available for my family and friends, and perhaps spend my days staying in shape, eating better, learning new skills, and getting outside far more often. So I'm planning for the gravy train to tell me my ticket has expired and kick me off in 5 years or so.
If you find your goals align even somewhat with mine, then congrats again because you've come to the right place! Because don't tell your office neighbor, but when you earn this much money, financial freedom is right around the corner if you do it right - and that's what we'll be figuring out how to do here.