There are bubbles in all fiat currencies and all things denominated in them these days e.g. stock & bond markets and real estate. So any sane investor is looking for something new that isn't manipulated by the central bankers ... that's why gold and silver are out of the equation ... leaving what? Crypto mostly.
Given how easy it is to get in the door and invest in crypto, I agree with Lisa_Brown that it's early days - especially for the big players -those with solid technology, solid teams, and a big vision. Also keep in mind that valuation of anything is speculative - so the bigger the vision, the bigger the speculation might become.
My bets are on MAID, ETH (+classic), and newby Golem ... all reaching crazy bubble proportions way beyond what they are now ... in fact I don't think any of them are even close to being in a bubble yet considering the massive fiat bubble & the size of their respective visions.