First, your theory that 'current time' is irrelevant is predicated on the broad market still producing relatively high real returns. This is by no means certain

First, your theory that 'current time' is irrelevant is predicated on the broad market still producing relatively high real returns. This is by no means certain, and "secular stagnation" asserts precisely that the high returns are over for now. Second, how about some division of labour? Instead of every individual learning about the optimal allocation of assets and the CAPM and so on, how about everyone just pays into a central pot while working, and a few specialists invest it optimally. (Different risk aversion can easily be incorporated in that framework.) Just like you and I don't build our own cars, and don't need to know about how it works and how to repair it to use it. That's how it should be done in the civilised world: you pay into a pension pot, and then when you retire you get a pension. And there's another benefit: instead of everyone having to save to cover their maximal possible remaining lifetime (with expected waste being maximal possible total pension minus expected total pension) everyone only needs to save to cover their expected remaining lifetime (with expected waste being zero).