What is diversification of portfolio and some of its key benefits? Why not to just invest on stock tips?

A portfolio is designed with assets which off-set risks of each other in the portfolio. e.g. Businesses moves in cycles which last 5 to 10 years. During the upcycle equities might be a good bet while during the down cycle debt or bonds will limit the downside faced by your portfolio. Even within equities certain equities perform better during upcycles such as Technology and capital goods and utilities and FMCG perform well during downcycle. By investing in stock tips you may be risking facing the vagaries of business cycles resulting in significant loss of value of your investments.