The problem comes if you choose the wrong niche and become overspecialized for that niche. It could be that at first that niche does just fine, but after some

The problem comes if you choose the wrong niche and become overspecialized for that niche. It could be that at first that niche does just fine, but after some number of years some technological shift might occur that would render your very specialized skills obsolete. That's the danger. Not saying that finding a niche is a bad thing, but you have to be flexible enough such that you can find another at short notice if need be.