In my personal opinion, I think pilots are just like another sector of society, in that they invest or plan based on what they are willing to risk.
Some pilots might invest in money markets, funds or commodities, some with a higher sense of risk, may start the occasional bar or restaurant. (Yes, it is a big risk)
And then there are those who invest in International trusts or securities, real estate in tax advantaged jurisdictions, or join with others in larger investments. (Those pilots are usually very well informed and understand the risks)
It really depends on what kind of research and preparation your willing to do. Then how much are you willing to risk...
And by the way, theres no such thing as too young to plan for retirement, one day you won't be flying, you may be married, you may have children, whatever the scenario, planning is never a bad idea.
I wish you the best of luck.