Sure, but it won't sustain itself at any mass. A black hole with a mass of 500,000kg lasts about 10 seconds and is harmless. If you managed to compress 300,000,000kg into a black hole you'd have it last about 100 years and it would still be too small to do any damage to the earth during that time.

You're correct there's enough mass in the solar system to create a self sustaining black hole though. Anything around the mass of the moon or larger we should worry. A black hole the mass of the earth would definitely be self sustaining, and about a centimetre across.

yeah but not sustain

I like to believe all that mass in an impossible tiny space is a result of all the multiverses stacked on each other.