I believe 99% crypto projects have 5 years lifecycle or even less. They become dead
That's why for longterm investment you'd be better of investing in altcoins with big marketcaps. They have enough money to keep their project alive.
Oyster turned out to be a high risk high reward project after the fall. I suspect the devs didn't sell enough at $3-$4 levels.
I also think that they did not do it. Otherwise, it would be frank fraud. Perhaps members of the team and sold their tokens, but the project fund is in place. The team can be trusted.