Let’s review his options:
dress like a homeless bum
dress like someone who cares about his appearance
Regardless of what he wears, he STILL MAKES MONEY.
Why do you care about his appearance so much?
The hyper-successful tend to wear what’s comfortable and focus on being hyper-successful. Steve Jobs, George Lucas, Stanley Kubrick, etc - the list goes on - all cared little about their appearance (in your terms), often unshaven and always wearing the same bland outfit. Jony works in a machine shop all day, so the appropriate outfit is a gray t-shirt and jeans and shaving only when stubble gets annoying; dressing up to impress you derails his thought process.
Methinks you don’t understand how utterly obsessed such people are. Changing mental gears to dress up is a problem when you’re juggling million-dollar thoughts all the time. Changing his outfit is, in a sense, lying: anything other than his daily norm attire isn’t who he is.