Why would one's desired tradeoff between risk and return of financial investments vary over one's lifetime?
Consider how people invest in different financial investments and activities during their lifetimes. (What different things do people do during their lifetimes? Education, work, vacation, marriage, buy a house, buy a car, start a family, retire, change jobs, etc.) Do you think these adequately balance the risk and return for people seeking to live their life as prosperously as possible?