Its the math!
FV of 100k at 10% over 20 years is 672,500 FV of 124k is 833.900
Factor in a reasonable future tax bracket and your still ahead with the traditional IRA.
First of all don't short change the Traditional, we were assuming a 25% tax bracket which would compare investing $100k Roth vs $133.33334k traditional.
Second of all you took an unreasonably high assumption of 8% that I threw out there, bashed it and took it to 10%, I would have lowered it to 6 or 7 and instead increase the amount of time until retirement to 35 or 40 years...
But why redo the numbers? I already had the $100k Roth investment at $1M and the Traditional at $1.33M. I'd guess you'd pick the traditional at $1 and 1/3 Mil taxes, I'd pick the Roth. One can also split if unsure.
Just thinking out loud here, if someone was 65 and was presented with a safe/lucrative investment and wanted to cash out let's say $500k from retirement fund in one tax year, it prob would suck if he picked the traditional IRA, no?