Most people need to buy a kit just to get involved as they need to have some kind of a starting point. Then threre's others of which I sense there are many or most types here that definately do not and are quite good DIYer's.
I myself have never bought a kit. Before coming here, I have built my own stringed instruments, amps & speaker cabs, business desk, numerous other wood working items & furniture, solid state effects pedals and amps down to etching & drilling my own circuit boards, radio controlled airplanes - motorized and gliders, reeftanks w/ sumps, refugiums, other misc tanks, replenishing and filtration equipment, lighting and electrical systems, irrigation and plumbing systems, and motorcycle, car, and boat engines and restorations. I even re-grip my own golf clubs, lol.
My point in all of this is NOT to toot my own horn rather that I know that when the job is done, it's done right and will last a long time if not outlast me. It has all of the features and works how I want it to, not how someone else wanted it or designed it. You don't get this with buying a kit. You have no control over parts or design quality. There's a lot of satisfaction and peace of mind achieved as a result of DIY and if something breaks, needs improvement, or just to change to be improved or upgraded for sake of seeing if something can be improved or upgraded (as geezer and tubenit knows,

) it's right there easy to do and w/ the know-how to do it. BTW, you guys ROCK!