The fact that companies such as Paypal work on such tiny margins and still need to charge 2-3% transaction fees suggests that the whole industry suffers from systemic inefficiencies, and that a shake up is long overdue.
Bitcoin doesn't have the costs that those companies have, so it can always out-compete them in terms of transaction fees. No bonuses, no middle management, no legal departments, no call centers, no red tape, no marketing costs, no office buildings, no dispute resolution, no chargeback, no cost from chasing fraudsters.
Sure, Bitcoin suffers from scamming too but these costs are carried by the scammed individuals, not collectively by all users as with Paypal and credit cards. Bitcoin users rely on a reputation system and take personal responsibility for how much risk they are prepared to take. That also removes the moral hazard and reduces system-wide fraud losses. Bitcoin users can also optionally use escrow, but again then they have to pay for the incurred costs individually.
The bulk of Bitcoin purchases hass been from investors so far.