Many others have wisely advised caution. This is an area which interests me as well. A lot. So have read a lot of articles and also some books on the topic (some may only indirectly apply to this topic)
- 'The Big Short' & 'Liar's Poker' by Michael Lewis
- AntiFragile by N N Taleb (There are other's by Taleb, which I haven't read)
- Seeking Wisdom by Peter Bevelin (on lessons learnt from Warren Buffet & Charlie Munger -- Yes, few of the most richest guys, who gained perhaps)[1]
I have also made some mistakes in investing. One so obvious mistake in hindsight, one was around 2007, when I moved a large portion of my networth from a single stock, to a diverse portfolio. Which was a good thing in itself, as I was moving it from all-eggs-in-a-basket to more distributed. But When the crash happened (world wide) I might have gone down 30%! The single stock, was comparatively down by much less. The good thing I did was not to do a panic sell in 2009. Though Discarded some stocks which were proven worthless (some down by 95%), just to avoid the pain of seeing them in my portfolio. But I kept the Mutual funds, which again started to come back to the original levels around 2011 and later on.
In restrospect, I should have reduced the risk fast. That is moved it all to cash. Then gone about investing slowly. By which I would have escaped huge downside (2008/2009). The problem is I knew the mantra already. But it got firmly registered after that experience. Another such golden rule is 'Buy when cheap, Sell when high'. Sounds very simple, but hard to grok it fully, unless you have felt some pain.
Having learnt that lesson. Now I keep most of my investment outside the stock market (exited during the rise of 2014). And keep only lesser amount around 10-15% in stock market. And that too only in index funds.
So IMHO, there is clearly no one size fits all. Investing and gaining from it is very much possible. Wonder if there is any vested interest in the mantra which gurus give i.e. invest only in mutual funds/index funds. Do they want others to not compete with them? :-)
But it does take a lot of time and years and pain to become good at it. And time is the biggest resource constraint, which perhaps we (the non-pros) all have. So at present I like to read everything I find on the topic. But decide to play it safe (i.e. fixed deposits, index funds, and similar). As once you are in the game i.e. investing in stocks/instruments which have huge upsides/downsides and hence riskier. You need to be more involved. And my personal experience its very difficult to do that, with things like programming and trying to grow your own business.
Hope this misc bit of reading pointers and micro experience share, is of tiny bit use. I am ever interested to read as much on this topic - views, articles, particularly the insights people learn from experience.
[1] Had got this reco via Derek sivers https://sivers.org/book/SeekingWisdom
Edit: typo