It’s not really the time. It’s more about the mental effort it takes to find out what to switch to.
Sure, it’s easy to install Firefox or sign up for Lemmy once you know that it’s there, but most people just have a sense that things suck with no idea of what they can do to fix it.
Finding out what to do to have a better experience takes a non-trivial amount of mental energy that scrolling reddit and instagram do not require.
The constant hustle, multiple jobs, or jobs with a high mental load, rising prices and stagnant wages all work together to create a lot of decision fatigue and stress. It often takes something major to get people out of that and get them active at changing things.