The only way to raise Bitcoin is the herd effect. It means that Bitcoin needs a massive investment. And when the course starts to take off, people will see it and also start buying Bitcoin. So it was last time.
More demand with less supply, most things rise in price that way so wouldnt be unusual. Last time it was about halvening but also a few things correcting over time. I've read people say BTC rose largely from alt coin inflation, I'm not sure that can be right but it helps raise general interest so I would call it utility development and application popularity. If BTC becomes more popular in use and useful then its helping raise the population of users and we see more natural demand