Even if people can't access a computer, can they access a mobile device? A tablet, cheap smartphone, anything along those lines? If they can then they can go ahead and use and buy bitcoin whenever they want. A computer is one thing, and I kinda understand why so many don't have this yet -- but a TON of people in the world have phones capable of using bitcoin, even in poor nations.
Your point is invalid.
No quality bitcoin wallets or miners exist in Smartphones (at least the ones i know)
We do have quality bitcoin wallets for our smartphones such as the Mycelium wallet and the Electrum wallet. No doubt both are the best out of all the others. We also have ledger nano and trezor which can be used by the ones who dont have an access to a Pc.
Whether or not bitcoin goes mainstream or not it will still be a successful cryptocurrency as it will be later used for making digital payments.