Why did the Beatles generate more income in one year than Albert Einstein did throughout his long career?
The reflexive answer is:
How many bands like the Beatles were there?
But, on second reflection, how many scientists like Einstein were there?
Rarity or scarcity cannot, therefore, explain the enormous disparity in remuneration.
Then let's try this:
Music and football and films are more accessible to laymen than physics. Very little effort is required in order to master the rules of sports, for instance. Hence the mass appeal of entertainment - and its disproportionate revenues. Mass appeal translates to media exposure and the creation of marketable personal brands (think Beckham, or Tiger Woods).
Yet, surely the Internet is as accessible as baseball. Why did none of the scientists involved in its creation become a multi-billionaire?
Because they are secretly hated by the multitudes.
People resent the elitism and the arcane nature of modern science. This pent-up resentment translates into anti-intellectualism, Luddism, and ostentatious displays of proud ignorance. People prefer the esoteric and pseudo-sciences to the real and daunting thing.
Consumers perceive entertainment and entertainers as "good", "human", "like us". We feel that there is no reason, in principle, why we can't become instant celebrities. Conversely, there are numerous obstacles to becoming an Einstein.
Consequently, science has an austere, distant, inhuman, and relentless image. The uncompromising pursuit of truth provokes paranoia in the uninitiated. Science is invariably presented in pop culture as evil, or, at the very least, dangerous (recall genetically-modified foods, cloning, nuclear weapons, toxic waste, and global warming).
Egghead intellectuals and scientists are treated as aliens. They are not loved - they are feared. Underpaying them is one way of reducing them to size and controlling their potentially pernicious or subversive activities.
The penury of the intellect is guaranteed by the anti-capitalistic ethos of science. Scientific knowledge and discoveries must be instantly and selflessly shared with colleagues and the world at large. The fruits of science belong to the community, not to the scholar who labored to yield them. It is a self-interested corporate sham, of course. Firms and universities own patents and benefit from them financially - but these benefits rarely accrue to individual researchers.
Additionally, modern technology has rendered intellectual property a public good. Books, other texts, and scholarly papers are non-rivalrous (can be consumed numerous time without diminishing or altering) and non-exclusive. The concept of "original" or "one time phenomenon" vanishes with reproducibility. After all, what is the difference between the first copy of a treatise and the millionth one?
Attempts to reverse these developments (for example, by extending copyright laws or litigating against pirates) - usually come to naught. Not only do scientists and intellectuals subsist on low wages - they cannot even augment their income by selling books or other forms of intellectual property.
Thus impoverished and lacking in future prospects, their numbers are in steep decline. We are descending into a dark age of diminishing innovation and pulp "culture". The media's attention is equally divided between sports, politics, music, and films.
One is hard pressed to find even a mention of the sciences, literature, or philosophy anywhere but on dedicated channels and "supplements". Intellectually challenging programming is shunned by both the print and the electronic media as a matter of policy. Literacy has plummeted even in the industrial and rich West.
In the horror movie that our world had become, economic development policy is decided by Bob Geldof, the US Presidency is entrusted to the B-movies actor Ronald Reagan , our reading tastes are dictated by Oprah, and California's future is steered by Arnold Schwarzenegger.