[treebog]

To a large extent, alcoholism is by chance, accidental, and without any known cause.

[jacobolus]

In many (most?) cases, not becoming addicted to alcohol is a straightforward result of deliberate repeated choices not to consume much alcohol.

There are also people who regularly binge drink and don’t become addicts per se... I guess you could call that both fortuitous and fortunate?

Or we can go all out and deny any human agency or choice, in which case I guess everything becomes fortuitous. This makes the word not very useful though.