Google has massive technological assets, but as an organization it has shown repeatedly that it is completely unable to leverage pretty much any of it as a viable business.

On the tech side they are excellent, but on the management/business/corporate culture side they have repeatedly proven that they are much less competent than pretty much everyone else.

Fortunately for them, they have a very prolific cow to milk with their ads business, and that's where they get their valuation from, but there tech is legitimately undervalued because they have repeatedly shown that they don't know how to convert that into business.