Not to mention that 600k in 12 years will buy a lot less than it does now, unless you're assuming that's a 12% real return (so 15-16% nominal return, assuming 3-4% inflation). Earning 15-16% CAGR for 12 years in a row is REALLY a stretch, IMO. But I don't know, my crystal ball is broken.

So that 600k is probably overly optimistic, and not in today's dollars.

Most people I've seen tend to assume a real return of 4-7%.

As far as the math.. it's close. I get 570k, not 600k. (Also it seems your contributions are over 4 years, not the 4 1/2 that you say.)

50k today, adding 30k annually at 12% for 4 years gives you ~$231k. Then letting that sit with no more contributions at 12% for another 8 years gives you $573k.

Yes? Or did I goof something up?

Assuming a 7% real return (what the stock market has done historically - 10% minus 3% inflation, for 7% real), you'd have ~$350k in today's dollars. Assuming a more pessimistic 4% real return, you'd have ~257K in today's dollars.