Expect possibility without ignoring probability.

Possibility and probability are different questions, and good judgment requires both. Something can be genuinely possible and quite unlikely, and pretending otherwise leads to plans that only work in the tail. Holding both lets you pursue long shots without staking everything on them.

When you are excited about an outcome, estimate roughly how likely it is and size your commitment accordingly. Keep pursuing it if you want; just do not build the rest of your life on it landing.