I know for me personally, I got into GRC this last month as a result of 2 main factors: my newly found interest in cryptos in general, and my previous use of the BOINC research network.

I had used BOINC years ago simply to donate my idle CPU power to scientific research of projects I felt were important and interesting. I did it then with no profit motive and no incentive other than purely humanist altruism. That is why I believe strongly in the GRC long term sustainability, because there is a large group of people who will always contribute to BOINC regardless of the profit motive, so it will only make sense that as more and more BOINC hobbyists like myself discover it, it will continue to grow and at a more sustainable rate than other cryptos. Unlike mining of other cryptos, people have been doing the work of mining for GRC before it existed, and they continue to even if mining becomes less profitable. If larger cryptos like bitcoin continue to become more diffocult and less profitable to mine, they will inevitably see a drop in overall mining power or a shift to higher fees per transaction, which puts a burdon on the network and the community, but GRC has an infrastructure that will not be subject to those same problems.

I know this is anecdotal evidence, but that's why I chose to be a part of GRC, and I'm sure I'm not the only one. I believe having access to the reasons why people get into GRC will shed light on whether the recent growth is suatainable or just a bubble that will burst.