Anything's possible, but the "It's just X" argument can be invoked so universally that I'm not sure it adds to the conversation.

ExxonMobil is just oil. WalMart is just department stores. Visa is just credit cards. All those companies have top-20 valuations. It's possible to come up with a doomsday scenario for any industry ... but by and large, once they get really big, they tend to persist in some form.

Google is "just advertising". What's your point?

I made my point. If internet advertising is an overvalued sector of the economy -- which it most certainly is -- then all your favorite companies need new business models. What more do you want to hear?

Why do you think internet advertising is overvalued?

It is only this year that internet advertising is projected to match TV advertising spend. TV advertising has been around ~50 years, and before that we have another ~100 years of print advertising to learn from.

From those historic precedents we can see that advertising is a huge, huge market. It is true that something could surpass internet advertising as the best way to spend that money, but I don't see any viable candidates (I'm including mobile & VR ads in "internet").

AdBlockers - of course - accelerate the trend of the money in the "internet" category going to players like FB where they control the delivery mechanism (ie, deliver ads in a mobile app, where an ad blocker can't reach it on most platforms).

And if cars are overvalued, then Ford needs a new business model. Kind of a tautology there.

There is no tautology and no conflict. Both would be true statements of their conditional claims were true. The trouble is that internet advertising is far more likely to be overvalued than cars are. I think everyone in the thread knows this and is just being a bit difficult for some rhetorical purpose.

Perhaps I am wrong about this, but it was my impression that increases in internet advertising revenue were mainly based on increased volume, not higher prices. I don't see any reason volume should drop when more and more consumers are using the internet and spending more time on it.

Consumers don't buy advertising. Companies do. Consumers don't want advertising at all, and they don't really understand that all their tech products/services are subsidized by ad revenue. Would they pay recurring fees for those products/services without an ad subsidy? Some would, but most won't. So if and when companies (that actually produce something) decide that their investment is better spent outside of search and social media, and if consumers don't then fund those products directly, it will be like an earthquake in SF. This is exactly what happened to newspapers, by the way.

Internet advertising spending replaced newspaper advertising. What is going to replace internet advertising? VR? Those ads will probably still be sold by FB and Google.

To me, Google and FB's PE ratios are sensible, taking into account current profits, continuing growth in the short and medium term, and uncertainty in the long run.

The insight the parent offered though is pointing out the tautology in the former case. Because while everyone knows Ford == cars, lots of people see SV/Google and miss that most of it is in the selling ads business and much less in selling tech.

Plus advertising aren't exactly the most stable form of revenues in a downturn. Some investors will be in for a harsh awaking at the next bear market.

That very much depends on the context of the ad business in question. What stage it's at in terms of expansion and so on. Google zoomed right through the great recession, growing its advertising business while most businesses were struggling. As far as Google's business was concerned, the great recession hardly happened at all.