I've always hated that analogy. Tylenol isn't the only profitable drug; Centrum Silver makes plenty of money too. Vitamins are perfectly respectable business.
Selling a Vitamin is a considerably harder sell than pain relief.
Some links for the size of the vitamin market vs. painkiller markets:
The largest vitamin company makes $80 million a year in profit: http://www.foodnavigator.com/Financial-Industry/US-vitamin-s...
The total spent on painkillers in the US is $11 per person, which comes out to about $330 million gross, which probably means less than $80 million total profit: http://www.euromonitor.com/Specialist_products_to_revive_ana...
[1] Except aspirin, which is being taken for its blood-thinning effect rather than its analgesic qualities.