Given enough time, anything with a non-zero probability of happening will eventually happen, and when you're dealing with the prospect of immortality, "enough time" is a given.

Even if the optimistic scenario is true for your first 100 "rezzes", the 101st civilization that takes over after the 100th collapses might not be so nice.

EDITED TO ADD: Moreover "the kinds of irrationalities that lead a civilization to do that kind of thing" is confusing a value judgment with rationality. An extremely predatory civilization might maintain its edge through cruelty, the same way that cats seem to play with mice before killing them. That would be evil, but rational.