I'm doing a PhD in Chemistry. My personal investments are (1) spending money to go to conferences (2) buying semi-respectable clothes I wear once a year (3) buying food that won't destroy my health.
I haven't got spare cash to get in on the ground floor of whatever cyberspace social hack that happens to be popular somewhere I don't live and is valued at a price I'm pretty sure is completely imaginary.
Your first move should be to hazard half a guess to your own question.