Investment diversification is necessary in business, it's not advisable to put your eggs in one basket, but before diversify, you need to carry out thoroughly investment analysis so that you don't end up losing your capital.
It helps reduce the risks which otherwise can cause harm and loss in the business. A reduction in the risk in other words means a rise in the profit and this is important in the current age.
reduction in risk != rise in profit; it means safety, nothing more - nothing less.
Warren buffet once said "Diversification is protection against ignorance."; but that doesn't mean the average person shouldn't diversify their wealth