I've seen this movie before. Actually, I've been in it. There were sequels. It took repeated beatings, but I eventually got the message.
It is possible to beat the market over short time frames, but in the end, a well-diversified, low-cost index fund is a lot cheaper , a lot easier, and a lot less risky.
I did pretty well in tech stocks in the 90's. I don't know who your advisory service is, but my advisor/newsletter service was "the Motley Fool." They were from AOL Message Boards and graduated to their own website. We all walked into a buzzsaw together. 90% declines. My last survivor (Cisco) took 14 years to recover. Much of my portfolio never recovered (bankruptcy). Motley Fool is still around, and a little more conservative now (they no longer pooh-pooh indexes). But their discussion boards are a shadow of what they were in the 90's. And I no longer do IPOs or even individual stocks.
The reference to the blindfolded monkey wasn't an insult. It was a quote from "A Random Walk On Wall Street." The question was whether or not successful stock picks are due to luck or skill. The blindfolded monkey obviously has no skill, so any success is due to luck. In a bull market, random selections will beat the market. (There have been multiple experiments confirming this. Some of them involved actual monkeys. The monkey portfolios beat 80% of professional Wall Street money managers.)
The caution is what happens when the bull market ends. If you were invested from 2007-2009, then you're good to go. You are likely to know what you're doing. If all your investing experience is since mid 2009, then be very careful. You've only seen a rising market.
As an experiment, keep some portion of your portfolio in a Vanguard Balanced fund, or the Total Stock Market Index fund. A single purchase provides diversification (you're buying several thousand stocks in one transaction). Then, over time, see how your individual stock picks fares against that TSM index.