Ask HN: (How) do you/I apply 80/20 principle to investments of $, time etc.?

I have been listening to the Business Method podcast on 80/20 principle [1] for a while. Maybe I have been missing something from it due to multitasking, but I am curious how to apply it to beginner level investing in stocks/funds.

My (European) bank, as probably other banks also, offers some free investing services. There are some "funds" to invest for free, comprised from many stocks from many companies and across different sectors and managed by some human managers. There are non-free investment options with seemingly higher ROIs, but I'd like to start with the free ones. I suppose (maybe I am wrong) that these "funds" are mostly non-volatile and may have some stable government issued stocks etc. My bank loves green energy, so there should be lots of stocks from this sector as well.

How do I apply the 80/20 principle and select the 20% of stocks/funds producing 80% of ROIs?

I suppose I could collect yearly data on ROI etc, available for these stocks, feed it to some regression program. Or just visualize ROI in quartiles and select the highest. But then should I compute p values for stocks with marked increase of ROIs?

In the podcast Richard Koch tells that it's easy to find high ROI companies per this principle, though may not be easy to invest in. I am a very basic level in investments with sparse knowledge.

How do you apply 80/20 principle in financial/time/etc investments?

[1] https://thebusinessmethod.podbean.com/e/ep554-hacking-the-algorithm%c2%a0of-business-finding-billion-dollar-investments-richard-koch-author-of-the-8020-principle/