Imagine I say to the tax office:
“hey. I’m a pro golfer. I want to take a tax deduction on all my golf clubs and fees at the golf club.”
“no. I’m still working full time and getting paid there. i’m just practising after work.”
“no. I haven’t made any money yet or won any competitions, but I in a few years I intend to win the PGA.”
“well. maybe we can agree i’m already professional and I can deduct all these expenses now and you can tax me when i make money later.”
“well. i guess it is true that you can still tax me later, regardless.”
“no. i can’t really think of any good reason why you should let me deduct the costs now.”