Many people get into stock markets thinking of making quick bucks, but this is the hardest place to make money. As pointed out in the book. In initial days, the focus should be on generating income rather than returns. And before investing in volatile assets, park your initial savings in low risk assets to build safety net. Which will come handy in times of emergency, when the going is though. And then start allocating your savings to volatile assets like stocks.
Also, IMO, investing is easy part, the hardest one is to stay put, especially during the drawdowns, with constant flow of information and looking at daily P&L fluctuations, even the slightest drop sends people in panic, leading to prematurely exit their investments. Many of us also try to time the markets, waiting for the next big drop, only to see markets rise all the way up.
There was this nice post by @parth111, I had read on the topic: Does it make sense to time the markets?
This one is worth embedding in your rule book:
“Your emotions won’t let you invest because the market is ‘high’ – and yet, if you had waited for yet another bottom, it would simply not have come. Most of the money in the markets is made by having a position, not by standing outside the airplane wondering if it’s a good time to get in.”