Imagine you're in your bathroom, choose two tiles and step from A to B.

No problem. What if those tiles were all you had to stand on and you were 30 storeys up suddenly it's a whole different equation and your body instinctively knows it. In fact some of parkour training is learning to master your own fear and confidently execute things you know you can already do in the face of higher stakes.

If I offered you a dice roll and said guess the number, bet 1 dollar I'll pay you 12 on the right guess you'd bet 1 dollar but you wouldn't bet your life on it even though the EV was high. Even if the payout was 1 million you still might not take it (some might)

Edit Thinking about it more, my example is more about factoring in all the risks - a positive EV bet with a large downside risk is not a great one to take even if the risks are small which is where the picking up pennies in front of a steamroller analogy comes from