The main push for regulation (at least from those worried about existential risk) comes from the fact that in the scenario that AI does get powerful enough to take over the world, it will be too late/useless to have a debate at that point. The only time where it makes sense to have a debate, from that perspective, is before the capabilities are developed. If such capabilities are developed, and we have no idea how to control such a system because we decided not to worry about it, humanity loses.