You don’t know your past selves. The older you get, the more you think you understand yourself as a younger person. You have probably forgotten how you were influenced then and might still have the same values. 

For instance, you might think that a priority as a child was to fit it. But, if really looking at your diary, you discover that you valued independence back then the same you do now.

Maybe you think the key to happiness is universal - that it is a constant in the changing world. However, the challenges facing this generation is not the same as that of the previous generation. Grandparents might have had trouble staying in touch, but they weren’t stuck on social media.

Those who "figure out" what life is really about, seem to focus a lot on the higher-order needs. They might have been workaholics and will cast judgment on their former selves.

People who already have a lot seem to assume that if they never strived for it, they would be happier. But, striving gave them their family, their network and their passions.

Don't worry about the Deathbed fallacy.  Don't worry about what some old version of yourself will think of you. Consider what you should do to become more fulfilled both today and in the future.