As a responsible rider, it's always good to know a few mechanical basics, things like how to check that your bike is safe to ride, fix a flat, and straighten the handlebars after a crash. In reality, that will get you out on a ride and then back almost every time, outside of a catastrophic mechanical incident.
Like it or not, all bikes require maintenance, just like a car or any other piece of machinery. Weeks and months of riding through mud, sand, snow, or whatever Mother Nature has decided to deliver will take a toll on any bike, no matter how much the initial sticker price was. This is why a lot of riders do have a fairly comprehensive mechanical knowledge when it comes to their bikes. In addition to being able to get yourself and your friends out of the woods by piecing together a broken bike after a mechanical, it cuts down on the cost of having to pay someone else to do it.
So, how mechanically minded are you? Do you lace wheels and perform every bit of service yourself, do you drop off your bike at the local shop after every ride for someone else to maintain, or do you fall in the middle, leaving suspension overhauls and full builds to someone else but taking care of the day-to-day stuff yourself?