They MAKE jobs. Most small shops out there is owned by a minority, it's often referred to as "Little Mexico" out here.
Restaurants, Supermarkets, Cell Phone Shops, and selling other goods. It starts small, but being in a position to actually own the property you live in and then gathering the resources from your regular job to invest in your local community or is key.
I'll give you an example, there was a local taco truck out here that operated for a few years...they collectively got their money together and bought a location in Downtown Lexington called "El Habanero Loko" which is right in front of the main public library in town, next to the local bus transit center, next to Rupp Arena where UK Basketball plays, tons of construction going on and a huge downtown project called "Centrepointe" underway. It was a very risky move on their part, but they might just make it. I would assume that if things go well they will likely move to another location that they BUY and not rent. I would assume that they don't own their location now, but I am not 100% sure on that.
On the flipside, I can't even imagine a scenario in where this can be possible in NYC. It will almost be like selling food out of a truck in the South Bronx and build enough wealth in a few years to open up a shop across the 42nd street train station in Manhattan or Downtown Brooklyn. Is it an exaggeration on my part? Yeah sure, but the point is still there. They were able to take the risk and are now right at the center of a very fast growing city with crazy expansion going on.
"Gentrification" in that area will be tougher because many own their property...good luck trying to convince a large number of people to sell their homes in a relatively short amount of time if you decide you want to change the neighborhood for profit.