Hi bkuehlhorn,
Let’s look at a scenario. Assume the prize is behind door #2 and goats are behind doors #1 and #3.
Scenario #1 for always switching:
1. You choose door #1
2.The host opens door #3 , because the prize is behind door #2, and asks if you want to switch.
3.You decide to switch to door #2
4.YOU WIN!
Scenario #2 for always switching
1.You choose door #2
2.The host opens door #3 or door #1 , because the prize is behind door # 2, and asks if you want to switch.
3.You decide to switch to door #1 or door #3
4.YOU LOSE.
Scenario #3 for always switching
1. You choose door #3
2. The host opens door #1 , because the prize is behind door #2, and asks if you want to switch.
3. You decide to switch to door #2
4. YOU WIN!
From the possible scenarios above where the prize was behind door #2 and you opted to always switch, you would’ve won 2/3 times from switching and lost 1/3 times for switching or vice versa you would’ve won 1/3 of the time by sticking with your choice and lost 2/3 of the time for sticking with your choice.