Sounds like you definately belong on the FIRE wannabee board. I don't have anything to add to your basic strategy. It is very typical of a logically oriented person and I'm not surprised you are an engineer. Over on the RECF board where I inhabit most of the time, many of us are engineers, software developers or involved in the finance industry and started out early just as you have.

Where I'd like to be at 50:
Working to stave off boredom more than anything else.

I felt just like you did when I was 25. However, after 20+ years as a software developer (I'm 45), I now look forward to ER (early retirement) in roughly 8 years. Each passing year, I think about all the other things I would rather be doing instead of working.

Just one example:
Yesterday, I was working out at a local HS track that is adjacent to a golf course. The course is at a rural location so not very busy. After my workout, I stopped to lay down on the grass to stretch out and observe the golfers meander up and down the fairways without being pressured, talking amongst each other etc.. How much I would love to be playing golf during the week when green fees are lower and uncrowded.

Sigh....

Anyway, congratulations on your prudent planning and God Speed that you reach you FIRE goals.

decath