I want to become a product manager. The alternative to joining the top tier consulting firm is to create my own startup or to find a PM role at a growing startup which will want to work with me despite the fact that I come from a biz dev background.
I agree with Tom Williams answer. Joining a top-tier consultancy will make you a better analyst and possibly communicator, maybe even think more "strategically". But it won't teach you anything about how to create a product roadmap, how to work with engineers, how to launch a product to market, how to empower marketing and sales, how to prioritize a product backlog, or write requirements, all of which are core elements of any product manager job.