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It’s hard to know few decades ago which companies to put substantial money in. It’s hard to know which companies will perform in the next few decades. And if you are wrong in your bets, there goes a few decades of your life and you can’t rewind the clock to try again.
If you’re retirement investing there’s there’s no need to make substantial bets in individual companies. 90% in index funds will get you to a reasonable retirement, 10% in something that looks interesting has minimal downside and significant upside because the value of money is non linear.
Assuming a buy and hold strategy at worst all your bet goes to zero which is unlikely, but there’s many companies that go to 100+X and hitting them can meaningfully boost your retirement. Gateway computers vs Dell wasn’t an obvious choice, but that’s a coin flip with huge upsides. Buy it in a given year and ignore it for the next 20, no you’re not going to time the market but you would see most of the upside.
I wouldn't fault anyone for just not doing individual investing. But, yep, if you're interested in putting in some time and think you have some insight into a particular sector, putting 10% or whatever into some individual companies you think are particularly interesting isn't a bad strategy. Some will flame out but maybe you'll hit one or two gems. It can also make sense to clean house now and then. I did that a couple years ago and I'm glad I did.