This has been discussed in other topics but not without leaving some issues unanswered. So DM has only gravity and does clump. Clearly even if it reached stellar density it would not intiate the usual nuclear 'burn' point because there are no electromagnetic/nuclear charges involved. But if it cannot be held apart by radiation pressure then why would it not carry on becoming denser - even to black hole proportions? I've read various vague notions of 'the particles pass through each other' etc but the consequences of gravitational attraction are increasing density or orbiting behavoir. This outcome has not been observed to be the case with DM so whats happening? Thanks.