The problem with loss leading is not people buying on their impulses though - the problem with it is that it is a tactic used to bankrupt the competition then milk the customer down to his last cent. It was de facto modus operandi of most Silicon Valley startups like Uber etc as well, and it has been very destructive. Loss leaders can do that because they already have a lot of capital to burn. So its basically the richer player bankrupting the poorer player in order to dominate the customer.