Stocks for the Long Run makes the pretty compelling case that over longer holding periods stocks are less risky than bonds.
Also, it should be noted, just because it's the optimal to have the most $'s that shouldn't be the goal. The goal should be to survive your retirement with "enough".
And it should also be mentioned, most people can't stomach holding 100% equities, for a very good reason. When the 40-60% market crash happens, people get emotional and make emotional decisions. Sure there are the lucky few that can hold out, but most can't. Are you going to be one of the few lucky ones? If you haven't yet been through it once(last one in the USA was 2008/9), how do you know for sure?