Make sure to include basic compound inflation because the figures given here seem to be hyperbolic.
100k principal, add 1k every month for 30 years. Compound at 7% --> 2M
50k principal, add 1k every month for 30 years. Compound at 7% --> 1.6M
Withdrawing 50k today costs you 400k in retirement
400k = 20% of 2M = 8 years of your 40 year career
50k today is worth more than 50k in the future.
(Consistent compounding at 7% is extremely optimistic, even before considering inflation at 3%+).
100k principal, add 1k every month for 30 years. Compound at 7% --> 2M
50k principal, add 1k every month for 30 years. Compound at 7% --> 1.6M
Withdrawing 50k today costs you 400k in retirement
400k = 20% of 2M = 8 years of your 40 year career