How much should you invest in the stock market? (from capital)

Greetings colleagues!
I decided to write an interesting post on the topic: How much should I invest in the stock market??
For me personally, this is an important topic and I think it will be useful for both beginning investors and people working with their own capital.
In 2007, I was invited to an interesting seminar related to investing (as I thought then). My brother and I were invited.
As it turned out, it was a seminar intendedlure people to Forex. They told me then that I would make good money, that I only needed to deposit a couple of thousand dollars)))) Of course, I didn’t have them then. My brother and I somehow collected $1000 each (at that time a dollar was worth about 30 rubles) and started trading on Forex. Of course, there was no algorithm of actions or understanding of the market at all!
And what do you think happened?
I remember now the first deal - 70% of the account,and then with two trades I wiped out the account. This was a blow to my hopes and plans for getting rich quick, it changed my vision of investing in general and gave me the impetus to comprehensively study the world of investing.
As a result, I came to the conclusion that it was on the stock marketmarket you need to invest 10-20% of your personal capital. Of course, professional investors can argue with me on this topic, but I am a conservative investor and the risk of investments is more important to me than high returns, since for me money is the time I spent on acquiring it, that is, I risk not money, but with your own personal time.
Your opinions on this topic will be interesting. Thank you for your attention.