The metal to insulator transition (MIT) at a finite coupling is a prototypical manifestation of strong correlations in many-electron systems. Its qualitative description is one of the key successes of approximate non-perturbative approaches to correlated systems, such as the dynamical mean-field theory (DMFT) and its extensions. However, definitive understanding of the MIT in one of the simplest models of lattice fermions, the 2d Hubbard model, has proven to be a challenge due to extensive antiferromagnetic correlations. The MIT predicted by DMFT is shifted dramatically when its cluster extensions are used, whereas diagrammatic extensions of DMFT suggest that the transition is absent altogether at any non-zero coupling. We approach the problem using diagrammatic Monte Carlo, an approach for numerically exact evaluation of high-order Feynman diagrammatic series, which allows us to obtain controlled results directly in the thermodynamic limit.