I'm suprised they've kept it going for this long and haven't yet started paying less in rewards to people.
I'm not sure if they're in some sort of deal with the developers they advertise to give them funds but I'd think that's likely since they're probably not boosting their own reserves anymore (altcoins have crashed quite hard in comparison to both fiat and bitcoin afaik - it's not much of an investment in their portfolio for the future if that coin no longer exists or has no volume in a few years).
But right now learn and earn is a waste of time I have the graph token until now it is stuck and can't able to trade or exchange for fiat or USDT.
I think they still do their money back on your first purchase too which is probably under half the amount you can probably get from learn to earn (if that's still a thing) - but it's a much simpler task.