Two sides of the same coin - building resilience and independence, having a "plan B" is effectively betting against everything working fine, risks not materializing and not needing any alternatives; no matter if it's about environment, software or politics.
However, I do consider it a good and prudent thing to "bet against" things that are crucial to us. Whenever there's a major threat, it's wise to also prepare to mitigate its consequences, since saying "we must prevent this" "we need to achieve X or the bad thing will happen" is, even if very true, often not sufficient, and betting everything on the expected success would be just naive wishful thinking, we definitely have to hedge our bets for everything that matters.
However, I do consider it a good and prudent thing to "bet against" things that are crucial to us. Whenever there's a major threat, it's wise to also prepare to mitigate its consequences, since saying "we must prevent this" "we need to achieve X or the bad thing will happen" is, even if very true, often not sufficient, and betting everything on the expected success would be just naive wishful thinking, we definitely have to hedge our bets for everything that matters.