She wouldn't be our "downfall" any more than any other recent major politicians have been. But she probably wouldn't improve things either.
I think you're being rather dramatic. I simply find Hillary to be unremarkable, in terms of what she is likely to do for the country.
Reagan was a governor. Nixon was a governor. Clinton was a governor. All great presidents. Carter and Dubya are exceptions to the rule.
“The reasonable man adapts himself to the world: the unreasonable one persists to adapt the world to himself.
Therefore all progress depends on the unreasonable man.” ― George Bernard Shaw, Man and Superman