If bike oil changes, fluid changes, and routine service maintenance were low cost (as they are for most cars), not as many folks would do their own maintenance. I like to do the fluid changes, etc. in part because I know a lot more about what is going on with the bike as it rolls up the miles. I notice stuff that needs attention or may need attention shortly. Plus, for me it's fun. Get a manual & get a good torque wrench or get a good mechanic - those are the options.
Does my dealer service dept. let me know what's wrong when they have the bike? Yes, usually, but their butt is not the one sitting on that seat - mine is. Do I utilize the dealer for some stuff - you betcha & I can be a picky SOB. For the "easy" stuff, I choose to do it myself & have never had a warranty issue arise because of that.
I know some who do practically everything & some who do practically nothing - even installing the simplest piece of chrome bling. They will run to a dealer or an indie even for a loose mirror - and that's what makes 'em happy. Does not matter to me, and it's their business, not mine. Some dealers & some indies take advantage - and as to which one does more of that - it's subjective. Trouble is, on some stuff unless you really know what is going on, you place trust in another to get it right. Some do a better job of that than others, and the tales on this board of bikes that sit in shops unridden waiting for some damn thing - indie or dealer - tell a sad story. I'd rather ride it that see it collect dust. Now I climb off the

Mike