Then, I'm afraid life dealt you a bad hand, but it's still no excuse not to care for your bicycle... You just need to get out and ride it a bit more now, Mr Spongefactory ;-)
What if you hate your brother and beat him up?
It's a shame that this is your experience. My kids (and the others we ride with) understand that they are lucky to have these bikes and take care of them. That said, ours get raced and there's a big difference between dumping the thing on the ground ("go and pick it up and park it correctly") and breaking them in a race ("At least you overtook him first!"). Care for it like it's your brother, but ride it like you stole it :-)
You must have very good kids who've been taught to look after things - most I see just throw their £500 bikes on the ground and wreck them in a short while! Parents with money (or at least credit) and no parenting skills. (annoyed)
This makes very good sense. I nearly pulled the trigger on a second hand very good condition isla beinn 20" for £200 but had to go for a 20" carrera from halfords. The family were paying and didn't want a second hand bike. Very pleased with he carrera though for £180. Very light and looks the biz.