Long term trading may be picked by those who has no extra time to watch the price fluctuations regularly. They are people who do believe in a project or at other coins that already has good development and willing to invest and leave they investment for a longer time. Less stess with this kind of investment.
Exactly. If I believe in a project, I will keep hodling for longer time even if the price goes up.
Also people have different periods in their life, when you're on vacation, you probably don't have time to check price every hour so you sell your day traded altcoins before you go on vacation and hold coins you believe in.