People naturally have a survivorship bias.

Thomas Ligotti has this great quote about why people, most people, are Optimistic (specifically with existence), that this is all okay, and nothing will go wrong, and that when things do go wrong, it'll be okay in the end

    “The point that in the absence of birth nobody exists who 
    can be deprived of happiness is terribly conspicuous. For 
    optimists, this fact plays no part in their existential 
    computations. For pessimists, however, it is axiomatic. 
    Whether a pessimist urges us to live “heroically” with a 
    knife in our gut or denounces life as not worth living is 
    immaterial. What matters is that he makes no bones about 
    hurt being the Great Problem it is incumbent on philosophy 
    to observe. But this problem can be solved only by 
    establishing an imbalance between hurt and happiness that 
    would enable us in principle to say which is more 
    desirable—existence or nonexistence. While no airtight 
    case has ever been made regarding the undesirability of 
    human life, pessimists still run themselves ragged trying 
    to make one. Optimists have no comparable mission. When 
    they do argue for the desirability of human life it is 
    only in reaction to pessimists arguing the opposite, even 
    though no airtight case has ever been made regarding that 
    desirability. Optimism has always been an undeclared 
    policy of human culture—one that grew out of our animal 
    instincts to survive and reproduce—rather than an 
    articulated body of thought. It is the default condition 
    of our blood and cannot be effectively questioned by our 
    minds or put in grave doubt by our pains. This would 
    explain why at any given time there are more cannibals 
    than philosophical pessimists.”