1. Speculative purpose - due to the spike in the fiat value of Bitcoin over the years, some believes the best way to make money is just to buy and Hodl Bitcoin.
2. Security - Some see Bitcoin as a means of securing their hard earned money not necessarily to make more money; this is especially the case in developing countries especially Nigeria where the value of the Naira usually depreciates overtime.
So rather than leave your money in the bank and see the value depreciate, why not buy some Bitcoins ☺
3. Trend - In some cliques Hodling is the trending thing; if you're not Hodling you don't belong. It's driven by a sense of being part of the next big thing.
4. Love - Some love everything about Bitcoin and the technology behind it (Blockchain). You can't blame them they're rich!
5. Forced - This is my last point, they bought Bitcoin at a high Fiat price and can't afford to let go at a loss so what choice do they have? Hold On to Dear Life 😕
What other reasons do you know?
from the list you mentioned, I assume that it only has a small percentage of the cause of people holding their bitcoins. While the biggest factor in my opinion is the confidence in the future of bitcoin will be glorious and think that bitcoin prices will continue to increase even though not through a smooth road. But it can all be easily ignored with a very high confidence in the future of bitcoin.