There are no definitive studies but reports I've seen suggest the typical software developer these days crosses that threshold about 20 years into their career. Something like 80% of all millionaires in the US are so due to 401k + savings, which is something software developers are exceptionally well positioned to easily take advantage of.

I know several non-software people in boring industries that managed to accumulate $1M in their retirement accounts by the age of 50 while living a non-austere lifestyle and making less money than the average software developer. It isn't that hard to do in the US. Anyone making above average wages with decent savings discipline can do it, the financial math makes that obvious.