The "it's too good to be true" reasoning isn't reasoning at all. It's simply a pattern recognition function to make our lives easier in a stagnant environment. It's a buffer. It allows us to absorb the impacts of the real world without getting rattled to the core by everything we see and here.
The downside from it making our lives easier and keeping us insulated is that it precludes us from really changing course, rapidly growing, or being flexible. As a child you can do all those things, but you don't have maturity and discernment. As an adult you gain those things, but many times you lose the flexibility, belief, and hope.