Silver today is different from a classic bubble situation in at least three major factors:
-It is an industrial input in industries with explosive growths, including solar panels and chips, not unlike say copper or nickel. There is a a solid demand for the metal.
-It is also, like gold, a currency play and a monetary reserve asset in an increasingly volatile global financial environment with growing debt.
-Its supply and production is limited, cannot scale up as much as for other metals in response to higher prices and greater demand, as most silver produced is a byproduct of the mining of other metals like lead or zinc.
This being said, I agree about the importance of a diversified portfolio.