Using the rocket equation, it is possible to compute the ratio between the $kg launch cost and $/kg material sell price that would make it economical.
Based on my calculations, with optimistic assumptions (including the asteroid being made solely of the desired material), you need 5 Falcon 9 launches and in-space assembly to bring back one ton of material, which would require selling the material for 350k$/kg for parity. But gold is only 80k$/kg, platinum is 30$/kg, etc.
Based on my calculations, with optimistic assumptions (including the asteroid being made solely of the desired material), you need 5 Falcon 9 launches and in-space assembly to bring back one ton of material, which would require selling the material for 350k$/kg for parity. But gold is only 80k$/kg, platinum is 30$/kg, etc.
Doesn't look feasible with current technology.