On the one hand, consequentialism argues that markets work better than most critics recognize. This is not to say markets work perfectly. But in the consequentialist assessment, market work well enough that the case for intervention is not obvious.
On the other hand, consequentialism argues that government works less well than advocates of intervention recognize. This is not to say interventions always make things worse. But in the consequential assessment, government causes sufficient problems that a presumption against intervention is reasonable.
None of this proves the consequentialist perspective is correct. The statements above describe consequentialism rather than “prove it.” Support for consequentialism must come from showing on on a case-by-case basis that markets work moderately well while interventions work badly.