In my early 20s, I focused more on investing in my career than in my retirement accounts. That means my expenses included everything from nicer work clothes to moving across the country following a work opportunity to games/entertainment systems to properly destress and dissociate from the rate race after hours.

I'm in my upper 20s now and only getting started on an FI track (just broke $10k, and it's very tiny but feels great). But if I hadn't focused on establishing myself first, the road to FI would be much more painful. Now, it might take me an extra 5 or so years to get there, but I enjoy my job and enjoy the place I work and live. Getting started 5 years earlier likely wouldn't have made much of a dent, and I'd still be stuck somewhere I felt miserable climbing a ladder I didn't want to be on. Instead, if I have to work closer to a normal retirement age, at least I'm going to enjoy those decades more than I would have otherwise, and now I get the benefit of being more financially secure than most my age.