As has been said repeatedly, it depends on what you work on. I need and use both everyday working on CNC and other machinery, and in building maintenance.
Brand new mills and lathes from Haas (USA) use all SAE. Doosan (Korean) and Mori Seki (Japanese) are all metric. All of our older machinery, conveyors, building infrastructure, wash line equip, mechanical systems and equipment, etc. are SAE. Okuma Howa (Japanese) and Trevisan mills are metric. Sometimes the conveyors attached to the metric machine is after market, SAE. We have both metric and SAE hydraulics. If somebody at work asked me to borrow an SAE socket smaller than 1-1/2", or a metric socket smaller than 30mm, I'd tell them they should have one. If they told me all they had was SAE or metric, I'd tell them they need to buy the tools to do their job.
Cars, for the most part, don't last like some machines do. The institutionalized use of SAE is prevalent, and would be needed for the next 100 years even if another SAE fastener never rolled off the line starting today.