There’s a theory which accounts for that called MACHO, for MAssive Compact Halo Object. While it’s possible, over many years of observation it’s very unlikely. You can’t see a black hole directly, unless it’s “eating” of course, but you can see gravitational effects like lensing. If black holes and neutron stars made up most dark matter, we’d expect to see evidence of it, and we don’t. It is still possible, although Weakly Interacting Massive Particles (WIMPs) are more likely, along with Axions and Sterile Neutrinos.