Is it foolish to run a concentrated investment portfolio?

Is it foolish to put all your "investment" eggs in one basket?

One key benefit I have found about a concentrated portfolio is the FOCUS and DISCIPLINE it brings.

Do you know it is extremely "easy" to buy stocks? All you need to do is open a brokerage account, fund it, click some buttons and off you go!

However, because it is sooo easy, many people don't take it seriously enough. They will spend days, weeks, even months researching the latest car they want to buy. But have no qualms listening to someone on Reddit or a social group talk about a stock and they proceed to put their hard earned money into it.

Well, I have found that by LIMITING myself to only 12 or 15 really good ideas, I FORCE myself to only select the really WONDERFUL ones. Which means I will need to be disciplined and actually DO THE WORK to figure out which of the 12-15 deserve a place in my port.

Do you have a basket of WONDERFUL eggs?

PS: You need to really know what you are doing if you want to concentrate. If not, stick to a diversified and well constructed ETF.