The likes of Megabus and BoltBus didn't exist before the Chinatown busses became popular. They were all spun up by the big old-fashioned bus companies as competition after they realized there was a market there. BoltBus, for example, is run by Peter Pan and Greyhound.

between boston and nyc was generally more expensive unless you were booking far in advance, especially for a busy time. If I wanted to visit NYC for a weekend, megabus would require booking weeks in advance for a specific time in both directions. Chinatown buses, you got off work, show up at the bus terminal, wait half an hour and you're on a bus. Massive convenience factor. And they drop you off and pick you up in chinatown, which is much more convenient than the stops for megabus in NYC.

Megabus is cheap because of Chinatown buses. When the DOT moved in and shut down a whole slew of buses (for good reason, mind you), Megabus raised their rates dramatically.

There's a weird pricing symbiosis between the two sides.