I'd say learn about money, tax minimisation, investment and law as much as it pertains to helping you achieve financial freedom or if you have that already, then riches.

Another good skill is how to choose a good partner. As in spouse not business. Get this wrong and it can undo everything.

Also how to raise children well if you plan to do that. Then add estate planning and inter generational tax!

And if you have all of the above sorted then learn about a worthy cause you can help.