America is filled with lots of poor people these days, and there’s plenty of money to be made off them.

With Wall Street already turning once-homeowners into renters in housing neighborhoods, billionaires and entrepreneurs are now investing in trailer parks, where they are making considerable fortunes off of raising the rent on the poorest among us.

The economic concept is as easy as shooting fish in a barrel.

Generally speaking, these people moved into trailer parks for the cheap rent, and even with rent prices soaring, these poor people have nowhere else to go.

“The economics are compelling… there’s a lot more poor people than rich people,” one investor said.

The London Guardian spotlighted this trending market for moguls, following a bus load of ‘boot campers’ at Mobile Park University who are learning how to profit from the poor, many of whom are ironically found immobile and ‘trapped’ in their mobile homes:

According to the Guardian:

Trailer parks are big and profitable business – particularly after hundreds of thousands of Americans who lost their homes in the financial crisis created a huge demand for affordable housing. According to US Census figures, more than 20 million people, or 6% of the population, live in trailer parks.

It is a market that has not been lost on some of the country’s richest and most high-profile investors. Sam Zell’s Equity LifeStyle Properties (ELS) is the largest mobile home park owner in America, with controlling interests in nearly 140,000 parks. In 2014, ELS made $777m in revenue, helping boost Zell’s near-$5bn fortune.

Warren Buffett, the nation’s second-richest man with a $72bn fortune, owns the biggest mobile home manufacturer in the US, Clayton Homes, and the two biggest mobile home lenders, 21st Mortgage Corporation and Vanderbilt Mortgage and Finance Company. Buffett’s trailer park investments will feature heavily at his annual meeting this weekend, which will be attended by more than 40,000 shareholders in Omaha.

Even for those who own their own trailers, the cost of moving them is insurmountable – with thousands of dollars to relocate a trailer too much a burden to escape the rising floor of rent prices.

At its worst, investors are becoming slumlords with a captive market of poor people, with new pressures from a market that is none too forgiving of the have-nots.

At its best, the opportunities are lopsided and seem to be squeezing those who can least afford it.

Today, the profits are virtually assured, with rent prices often ‘more than doubling’ over night.

“Raising the rent is typically part of the day one purchase, because often the ‘mom and pop’ [previous, family-run owner of a park] has not raised the rent in years so it’s far below market.

“We traditionally raise our rents by an average of 10% a year or something like that, and it’s pretty much true for the industry. Our world record [rent increase] went from $125 to $275 in one month.”

Not so much back in the 50s and 60s. America was too affluent then, and this kind of investing in low income mobile home housing wasn’t possible – or at least not readily profitable.