Regardless of whether bitcoin is in a bubble, a brief glance at its price-chart makes it quite evident that it is "in bubble territory."
To be clear, those are 2 separate points. Being "in a bubble" is not the same as being "in bubble territory."
It clearly seems to be in a bubble, and many commentators may seem justified in claiming that it is.
However, we are dealing with a completely new and unique market here. Even the wisest and most experienced observers do not know what the true value of bitcoin is, or what it will be a few months from now or a few years from now. Or tomorrow, for that matter.
With gold and silver, we have hundreds of years of history to determine what their current prices should be, in terms of various historical metrics. With bitcoin, we're discovering the price and the value as it moves.
We can make educated estimates, but so much is still up in the air that many predictions, estimates, forecasts and guesses will be far off the mark.
The best strategy is to keep getting more educated about bitcoin and cryptos.
As for the numerous alt coins, that in itself is not a major cause for concern. There are hundreds of fiat currencies, some of which overlap in terms of use, and transfers and exchange are common. With cryptos, transfers and exchange can be accomplished much quicker and easier. So, let a hundred flowers blossom, and a thousand cryptos contend ...
That said, many (or some) cryptos will most likely prove pointless, valueless, and "use" less.
(My feebly educated guess is that bitcoin (bitcoin cash?) and steem (among others) will continue to blossom and contend.)