Why hold? Because it is going to go up and down a lot, but you don't know when. You have to be holding it when it goes up.
Why up? Because it is the only legitimate digital cash on the planet:
1. Fungible (due to transactional privacy).
2. Non-inflationary but sustainable (due to tail emission comparable to gold supply expansion rates).
3. Scalable (due to adaptive block sizes).
(A) There is no freedom without privacy. (B) Everyone wants to be free. When they figure out (A), we all win.
Why legitimate?
1. Legitimate open source peer-reviewed, mature and trustlessly cryptography.
2. Legitimate altruistic community-driven meritocratic development and project management.
3. No IPO, no pre-mine, no centralization, no corporate control, in short: No rip-off.
I consider XMR to be the most important enabler of human dignity and liberty in the history of technology.