I appreciate how you state that investing has become an internal part of personal finance. I agree with you, but unfortunately nobody taught us this where I am from.
Same for me, other than tidbits I got from my parents occasionally. Like many of the important things I learned in life, I had to teach myself.
But for investing the market cap is irrelevant, the stock price development is relevant, dividends are relevant, interests are relevant. There are a lot more indicators which are more relevant if you want to invest in a company or not than the market cap.