What if the Bitcoin was in notes and with the same value as it has now, do you think anyone would misplace it or even walk with it on the street. Eventually you see a Bitcoin note will you return it to the owner. Let's be sincere and also see it as fun.
You should understand that Bitcoin is a digital currency and unlike like those fiat currencies (paper money) it can't be seen or held in hand. The question of what if doesn't make any sense cause though Bitcoin and fiat are currencies, their mode of operation is different, the fiat currency is controlled by the Government through it's Central Bank, while Bitcoin is not controlled by anyone but operates through it's blockchain. Moreover, I feel Bitcoin wouldn't had it current value if it was in form of paper, then it would definitely be manipulated by the government and lose it value like most fiat currency currently. What makes Bitcoin have more value is it's scarcity and once it's in form of paper money then it would be easy to see around making it lose more value, also 1 BTC is worth about $68k currently how do you expect people to carry that about in their physical wallet?.