Beware the sometimes subtle trap of thinking that, since you have thought about a big decision/belief at seemingly random intervals for a whole week (month, year) now, you have perspective on the decision/belief from a representative variety of your states of mind. State-dependent memory, habits, priming &c. make this unlikely unless you were deliberately making an effort.

Ignoring sweepstakes as such[1], a focused rationalist should regard all bets with odds far from a coin flip with suspicion; there are often better bets, and with more information for calibration.

[1] Perhaps justifiably, as the "may" in the title of this Discussion post implies more uncertainty than you find in a typical sweepstake scenario where the fine print and simple arithmetic are enough calculation in themselves.