Let’s assume that we – as a species – are not as smart as some of us think we are. I think that this is true (even if sometimes overstated), and that realising that it’s true allows us to accept that sometimes, we don’t know what’s best for us.
Recognising that we are irrational choosers doesn’t tell us how to solve the problem. My post, linked above, makes the case that we should accept that “nudges” or “benign paternalism” are acceptable. But you could object that even if we don’t know what’s best for us, we’re still better at knowing our own wants and desires than anyone else could be.