There are so many and such varied and awful things that can happen to any one of us at any time that it simply doesn’t pay to worry about them. If there are some real threats that you can prepare for or guard against, then it’s good to make those preparations or mount that guard, but otherwise… ?
To those ends I’ve saved and invested for most of my adult life, with varying degrees of success and care, hoping not to outlive a “livable income” that I can provide for myself, without depending on Social Security or any other form of welfare. That would have bothered me. I’ve pretty much gotten to the point where if the economy doesn’t go all to hell, then I may be able to provide for myself (as long as I can live independently) for enough years to live out a natural life. And as for “guarding”, I have decent locks on the doors and windows and live in a more-or-less safe neighborhood. I try to eliminate obvious hazards around the house and yard, and I drive a well-maintained car safely.
So I guess my biggest fear, if it came to that, would be a loss of independence: a crippling illness or historic economic wipeout that could impoverish me as I become less able to earn an income, or which prevents me from even finding or making a job (though I can hardly imagine that scenario, it’s out there).
I think the biggest thing that I would have to worry about aside from that, though, would be “loss of desire” ... to live, to laugh, to love, to want to participate, whether I did (or could) or not. If I didn’t “want to” live, then… I probably wouldn’t.