I generally do invest in people directly, just as I do in aggregate. The problem is when you help people one on one your reach has a large impact burt over very few people.
I have many times in my life taken homeless people into my home and invested in them to get a start in life. In some cases they have stayed with me for a year or more, and in some cases I have even paid for their university fees.
About 50% of the time it works out and the money and time is well spent. But I can at most do this for about one person every few years. It doesnt scale well. Sadly if I just give people money 99% of them never achieve anything with it, it only ever works with strong guidance and oversight, and even then at only a 50% rate. So overall while I do find this important due to the small number of people I can reach it isnt typically the bulk of the time and effort I put into helping people anymore. Especially because now investing that time into making large amounts of money I can reach and help far more people