My two cents having practiced several.

Almost all of them are useful in that they are a form of physical activity. They can keep you in good shape, and can also help you develop discipline.

Many are more art than practical. Arts like krav maga or kali are more geared towards practical use (self defense).

There is also a thing you can generally think of as “energy” that arts may have that often trend to make them not very practical against arts outside of themselves. For example, if a wing chun practitioner attempts to trap with you, and you’re a boxer, it just doesn’t work. It’s somewhat about range, but also the general “feel” of the art as well. JKD attempts to deal with this by teaching different arts that can be used within different ranges.

My one instructor also likened martial arts to technology, saying that they must evolve over time or just end up becoming ineffective for self defense.

The best thing to do in a situation, if you can, is to just escape. Your wallet is not worth your life.