Nothing is stopping you... Anyone can fork bitcoin or duplicate it and lots of people have. There are tons of 'Bitcoin' duplicates currently running, some with changes to the code and some with none.

The difference is noone knows your coin, no exchanges support it, noone wants it so it's utterly worthless. Saying "what if I had the power to convince everyone to use it" is somewhat fruitless. With that logic why not create your own commerce platform or search engine and ask the same question about Google or Amazon.

The Bitcoin cash developers tried exactly that, threw a ton of money into a well orchestrated campaign to say they were the true bitcoin... Whether you believe that or not is beside the point. They're not bitcoin. Bitcoin is bitcoin and until another coin takes that mantle, assumes it's ticker and replaces it on all exchanges, wallets, websites, hearts and minds etc etc only then could it be called bitcoin.

Short answer, nothing is stopping you. But I'd like to see you try :)