"Everyone should just be smarter/more educated" is what I used to think as well. I now fully understand some people have no desire to be educated in any way and it's a net good for society to not have a large % of devices compromised.
Now my in-laws (similar age) one very demented, the other thinks he knows best because he was a chemical engineer...they could use some built in protections
so ultimately I think some default level of "guardrail" is appropriate, but it should have a not too burdensome escape hatch
Which is really exactly what google is implementing here and why I'm so perplexed so many people are upset. You or I or smart parents (my mother has never used a computer in her life and wouldn't want to) will have absolutely no issue sideloading apps after the proposed changes.
The logical conclusion is that fdroid should be allowed and google play banned by default.
There's not an easy answer, but the non-answer of "people just need to be educated" is trivially dismissed.