Dealers in taboo products, like gun manufacturers, have even been the subject of recent presidential policy debates. Hillary Clinton and Bernie Sanders recently sparred over whether Congress should pass a law holding small arms manufacturers liable for crimes committed with their weapons.

Those who pay close attention to the debate over gun control in America, however, might be surprised to learn that in dollar terms, gun dealers are fairly low caliber. Revenue is just around $16 billion annually, far less than the sales totals of many of the world’s largest vice industries. Here are the top five.

1 Alcohol

There are few products as universally beloved as alcohol.

The World Health Organization estimates that global consumption of alcohol comes in at roughly 6.2 liters per person per year, or 13.5 grams of pure alcohol per day. Unfortunately, demand for the product is as strong as it is detrimental to health: The WHO estimates that alcohol is the cause of 6.6% of global deaths each year, or 3.3 million people.

But neither government intervention nor the health implications of alcohol consumption stop people around the globe from spending their hard-earned dollars at the bar. According to P&S Market Research, total global sales of alcohol reached roughly $1.2 trillion in 2014, and it's expected to grow faster than 3% per year for the next five years.

2 Tobacco

The tobacco industry has lost considerable power over the past generation, as the health risks associated with smoking have been widely acknowledged and governments have gotten serious about passing laws that either restrict the habit or make it more expensive.

But trends like falling cigarette sales and lower tobacco production here at home belie how profitable the industry remains on a global scale. According to market research firm IBISWorld, the global tobacco industry had sales of $528 billion in 2014, while revenue growth had increased on average by 1.6% per year in the five years prior.

3 The Military Industrial Complex

While the manufacture of handguns and other firearms for average citizens is a relatively small business, selling military-grade weaponry and services is another matter.

Companies like Lockheed Martin in the United States or BAE in the United Kingdom bring in huge revenues each year equipping the world's most powerful militaries with advanced weaponry. According to the Stockholm International Peace Research Institute, the world's top 100 military arms and services dealers post collective sales of more than $400 billion annually.

4 Illicit Drugs

The world was reminded of the immense power and wealth of global illicit drug barons when Mexico's most famous drug lord, Joaquin "El Chapo" Guzman, staged a daring escape from prison last year using a nearly mile-long tunnel that stretched from the jail's shower to a nearby residential neighborhood.

Guzman, who dominates the flow of drugs from Mexico into the lucrative American market, was estimated to have a net worth of more than $1 billion by Forbes, making it easy to understand how he can afford the necessary bribes and manpower to pull off such a feat.

But Guzman is just one of many people around the globe who have made fortunes selling drugs. The United Nations estimates that total revenue for the illicit drug trade is around $320 billion per year.

5 Gambling

Legal gambling in America was once unheard of outside Nevada, but state governments' endless search for revenue has put an end to that. As state authorities from Pennsylvania to Washington have begun to welcome casinos and the associated taxes, the gaming industry has exploded.

But it's not just in the United States where the gambling industry is thriving. According to IBISWorld, global gaming and casino revenue will top $278 billion in 2016, after growing by 2% per year over the past five years. Meanwhile, "the center of the Global Casinos and Online Gambling industry has shifted from the United States, specifically Las Vegas and Atlantic City, to China (i.e. Macau)."