OP why are you ignoring PP's comments about neurodiversity? Any or all of autism, ADHD, dyspraxia, sensory processing disorder could be relevant here.
My eldest has v similar issues but is one of the brightest in his class. He's autistic without any learning disabilities.
*obsessed with gaming - intense autistic focus
*won't brush his teeth - sensory processing issues
*can't tie shoelaces or ride a bike - motor skills issues, dyspraxia / common with autism too
*spends money instantly - impulse control / executive functioning, autism / ADHD
*bisexual - I've seen it suggested that the autistic community has a far higher proportion of LGBTQ people than the general population (only in passing from autistic twitter, there may be more to it)
*14 - not much you can do about that except give it a few years 
Is anyone else in your family quiet / focused / introverted / "quirky" or with similar sensory or motor skills issues?
Tbh if you're not even willing to consider there may be more to it than laziness i'm not surprised he's fed up.