In theory the share of the economy devoted to advertising should grow as the economy grows and becomes more complex. The more choices consumers have, and the more their base desires are already satisfied, the harder you have to work to convince them to buy your product. The harder you have to work, the bigger the rents that firms who already have control over peoples' attention can charge.
Similarly, the share of the economy devoted to the legal profession grows in proportion to the number of externalities in the economy (= the chance that some third party unrelated to your transactions will be wronged by your actions), and the share of the economy devoted to finance grows in proportion to the rate of change in the economy (the role of the financial industry is to destroy obsolete industries and redirect that capital into new, more modern ones; demand for its services is proportional to the number of opportunities there are to destroy incumbent industries with new technologies). The gains are at the expense of primary producers (natural resource extraction and manufacturing, and to a lesser extent retail, which is a complement of manufacturing). All of these effects fit observed recent history well.
There's no reason that this is a bubble except for the fact that once the rentier classes - government, finance, advertising, legal, real estate - have consumed the bulk of the economy, those previously employed in the destroyed industries tend to revolt, politically. In other words, the bubble ends with the destruction of society. Note that the usual outcome here is that the new rentier classes end up deploying their capital to hire outside allies and kill all of the people rising up against them, so I still wouldn't want to be on the side whose industries and skillsets have been destroyed. Historically, what tends to happen is that the whole society ends up marginalized, and some other world power who stayed out of the fighting ends up on top. (See eg. the French Revolution, where the peasants succeeded in killing the nobles...and then followed a century of wars and alternating dictatorships & republics, and when the dust settled, France had been eclipsed successively by Germany, England, and the U.S.)
Similarly, the share of the economy devoted to the legal profession grows in proportion to the number of externalities in the economy (= the chance that some third party unrelated to your transactions will be wronged by your actions), and the share of the economy devoted to finance grows in proportion to the rate of change in the economy (the role of the financial industry is to destroy obsolete industries and redirect that capital into new, more modern ones; demand for its services is proportional to the number of opportunities there are to destroy incumbent industries with new technologies). The gains are at the expense of primary producers (natural resource extraction and manufacturing, and to a lesser extent retail, which is a complement of manufacturing). All of these effects fit observed recent history well.
There's no reason that this is a bubble except for the fact that once the rentier classes - government, finance, advertising, legal, real estate - have consumed the bulk of the economy, those previously employed in the destroyed industries tend to revolt, politically. In other words, the bubble ends with the destruction of society. Note that the usual outcome here is that the new rentier classes end up deploying their capital to hire outside allies and kill all of the people rising up against them, so I still wouldn't want to be on the side whose industries and skillsets have been destroyed. Historically, what tends to happen is that the whole society ends up marginalized, and some other world power who stayed out of the fighting ends up on top. (See eg. the French Revolution, where the peasants succeeded in killing the nobles...and then followed a century of wars and alternating dictatorships & republics, and when the dust settled, France had been eclipsed successively by Germany, England, and the U.S.)