In my opinion, the majority of people who were successful today started from personal skill or self development, after which before they started investments.
Personally development is also part of investment because you have to invest in yourself because you can talk about going out to invest in a business venture so without investment there will be no true wealth because such wealth even when they come doesn't last because there is no proper understanding of what investment is, so what you should know is that personal development is also part of the investment process