overhope

Excessive hope or anticipation; presumption.

If the good turn out less than you hoped for, good though it be, yet because it is not so good, it seems to you more like a loss than a gain, by reason of the overhope.

Hopefulness; sanguineness.

To hope excessively; presume.

If we have overhoped ourselves in the hay we may have done the same with the hogs.

I'll cast this observation a little too broadly to make the point clearer: many principals "overhoped" that computers would have miraculous effects on all students exposed to them even if only for a few minutes per week, and now finding …

To hope constantly.