because bitcoin is still new. moreover there are still many people who don't know what is the world of bitcoin. it's the bitcoin barrier to legitimate money. but I'm sure that bitcoin will someday become a legitimate currency like paper currency
Sure some day Bitcoin will become legit as paper or fiat money but Bitcoin need atleast 51% formal agreement for that to happen which is not happening at the moment and even it is happening it is in a slow rate right now but we can hope that will happen in the near future so many can use it without hesitation to make there payments and for there core business transactions to develop there functions further with better efficiency and security