I don't know if it's just about getting people to trade there, sometimes it might be more, one might eventually trade on that exchange and pay those fees, but there might be more.
Probably. I imagine some other required task will spring out of no where for you to complete once you unlock your tokens. They might tell you the trading fees partially unlocked the tokens and there’s just one final thing to do to fully unlock them.
As for your lecturer, some people I know got into crypto through the wrong project and it has marred their expectations and this isn't even good for the adoption of crypto in the long run.
It is especially difficult for first timers who unfortunately joined a ponzi scheme in an attempt to invest in crypto to ever believe that crypto is anything aside a ponzi scheme. After their first time experience, their minds are made up and nothing anyone says matters anymore.