I waited a relatively long time before buying an ND filter.
ND filters allow you to expose for a long time even during the day. The stronger the ND filter, the longer you can expose even in bright light.
All you need besides the ND filter is a tripod.
Such pictures look best when something moves continuously and another part of the picture remains unchanged at rest.
Play a little with the exposure time and you will get a satisfying result.
It's really not witchcraft. The image has an exposure time of 3.2 seconds and an ISO of 64.
Camera used: Sony Alpha 7 III
Postprocessed with: Lightroom