absolutely. while repairs skills and bicycle know-how are good things for cyclists in general, wrenching your own rig makes sense from an economic/opportunity cost perspective too as it saves time, money and the stress of waiting for repair work to be done (and wondering if somebody competent made the repair). yes, the LBS is a little more flexible in the fall/winter - but still, if something goes wrong on Saturday and you're racing Sunday too (it happens!!), doing your own repairs is invaluable. knowing how stuff works also helps to develop preferences for components, which can lead to more comfort working on your own bike, which leads to keeping everything dialed-in for race day.
Why ride bikes if you don't work on them? Isn't that why we ride, so we have something to fix?
The vast majority of my bikes started as me getting just a frame and transferring parts from older bikes onto the new frame. My last bike (even though I spec'd the components) was put together by my LBS. I forgot you could buy a bike that way.
In all seriousness, working on your bike is not hard. And once you grasp a few concepts, everything comes together. The number one thing that's has helped me over the years is to always get the right tool. If the mfg says you need a special tool, get the tool. It'll turn a hard job that you'll probably screw up, into something very easy. So, if you're going to work on your bike (which I'd highly recommend), get good quality, proper tools from the start.
I do all maintenance myself on all my bikes. I wrenched professionally for a few DH race teams, and I have been doing all of my own work for about 9 years now.
It is incredibly easy once you get the correct tools and the correct procedures. I try and show everyone how to build and true a wheel as this is an invaluable experience and will save you a few bucks in the long run.
As for tools, slowly purchase new ones as needed. A full set of allen wrenches, chain whip and cassette lockring tool are some of your first tools that you will need to do basic cleaning and maintenance.
Enjoy learning more about it and have fun!!!
Don't forget cable cutters to add to the starter kit
i do most all of it, but i still don't like cutting stearing tube! but i have done it.