Me, hired at 39.
upgraded at year 4
Put 6% in as a FO on top of the 16% DC
Have maxed out personal contribution to 401k since upgrade. I put in 10% and am forcing money to the MBCBP. I fill the personal contribution april-may time frame and usually am forcing the 401k excess to MBCBP by September or first Oct paycheck.

My estimated 401k at 65 in 2044 is looking to be $6m or so.
This is based off maxing out 401k and 9.5% return

I had about $120k in 401k/TSP when I started at Delta.

That 6M will be worth $3.5M if current long-term inflation stays the same.