The two sins against Hope are despair and presumption. St Thomas tells us that presumption is an immoderate excess of hope where we presume prematurely (whilst still alive) that we possess eternal salvation. Despair is the opposite. Giving up hope prematurely of ever possessing eternal salvation. Both, Aquinas, says are sins against the Holy Ghost. (ST II-II Q art 20 & 31)
Seattle Catholic's optimism, "no matter what, life is good, after death life will get better," seemed to be more like 'presuming' than 'hoping'.