Without kundalini purification, entering Samadhi or higher trance could lead to reappearance or manifestation in a subtle state or it could cause physical rebirth as a baby.

One may take such a big risk of entering into samadhi in a subtle world, because one has no choice in the matter if one practices yoga and one loses a physical body and is left only with a subtle one?

Samadhi does not necessarily stop the mind’s vrittis but it may do so on occasion. During samadhi the kundalini will do its utmost to resume the vrittis. It may do this with or without the permission of the observing self.

The key issue is the objectivity of the observing self. If it loses objectivity, there is no telling what will happen as to where it will become aware of itself again. It could be here or there or up or down or in or out which include waking up as a trapped form in an animal’s abdomen.