Diversification is not bad, and you can be wealthy doing it, but it takes a long time.

When I was in school in the late nineties, I bought AAPL. I held and added to it throughout 2000s. Just before the financial crisis of 2007 I was graduating from university and going to start my job in Houston. I sold most my AAPL stock and it was enough to buy my first house outright. Before I started my first real job. The timing turned out to be most excellent because it was the right time to get out of the market.

After that I continued investing in AAPL from the depth of the market crash, and started investing in NVDA. A close friend of mine got a job there and mentioned how nicely run company that was at the time.

I invested heavily in NVDA. Rest is reality :)