The Most Important Security Advice of all

The task of protecting your PC from infection is similar to crossing a busy road unharmed.
There are two, very different ways of crossing that road:

The first way is to be very careful about where you cross and to be watchful and aware of the dangers. In other words, make sure you don't get hit. The other approach is to protect yourself with something like an army tank and cross anywhere, anytime. If you get hit, you rely on the tank to protect you.

Now no sensible person would adopt the latter approach to crossing a road, yet when it comes to computer security that's exactly what many folks do.

If you want real computer security, you need to adopt safe computing practices rather than rely totally on security products to protect you. No security product or combination of products can or ever will, provide perfect PC security just like no car can provide you with perfect road safety.  With both cars and PCs you need to be careful  in your own behavior.