It's worth noting that this is targeted at FIRE folks - people who want financial independence (don't need to work to live) and want to retire early. To be able to retire 10+ years before the average american, you want to have a much higher degree of confidence that your financial plan can sustain you for 30/40/50 years. That requires much more complicated financial planning.
Or you can just max our your 401k, IRA, HSA, save enough of what's left over to make sure you can have a comfortable retirement at 60ish. The math for everybody else actually isn't as tricky as it seems for mid-to-high income folks. It's generally more about reigning in spending than fancy spreadsheets.
Best to figure this stuff out sooner rather than later, your future self will thank you. Don't bury your head in the sand on retirement. I ignored retirement planning until I was in my mid 30s, I wish I thought about it more before then.
Read "A Random Walk down Wall Street" and start investing.
Or you can just max our your 401k, IRA, HSA, save enough of what's left over to make sure you can have a comfortable retirement at 60ish. The math for everybody else actually isn't as tricky as it seems for mid-to-high income folks. It's generally more about reigning in spending than fancy spreadsheets.