The Bostromian argument for a Peggy Sue timeline
1. Most timelines contain the potential for enough technology or magic to allow someone to go back in time to fix the mistakes of the present [source: anime and fanfiction]
2. Most times people try this, they will only mess things up worse, sometimes requiring hundreds or even thousands of timelines before they complete their mission [source: ibid]
3. Therefore, the "original" timeline will spin off hundreds or thousands of Peggy Sue timelines, each with about the same population as the original.
4. The vast majority of person-instances will therefore be living in Peggy Sue timelines, rather than the original timeline.
5. Anyone without any special information on whether they are on an original timeline or a Peggy Sue timeline should conclude through anthropic reasoning that they are probably living in a Peggy Sue timeline.
The anti-simulationist corollary
1. Most simulations will not allow separate Peggy Sue timelines, since they require immense computational resources (and in cases where each Peggy Sue timeline allows other characters to spin off their own Peggy Sue timelines, potentially infinite computational resources before resolving).
2. Most Peggy Sue timelines will not allow simulations, as this will mean millions of suffering people being kept deluded, and any true hero or heroine would go back in time to prevent them from being formed.
3. Therefore, Peggy Sue timelines and simulated universes are mostly mutually exclusive.
4. There are few good reasons to run ancestor simulations, but many good reasons to go back in time to fix your past mistakes.
5. The number of simulations is limited by available computing power in the lowest-level universe, but the number of Peggy Sue timelines is limited only by the plucky determination of anime heroines to never lose hope, no matter how dark the path or many failures they have suffered.
6. Therefore, there are more Peggy Sue timelines than simulations.
7. Therefore, you are probably not living in a simulation.