Personally, I don’t bother connecting to a wifi network anymore (except when I’m at home or at work) because the mobile network is just so fast and convenient.
Even when abroad, I just buy a local SIM card and use that.
I could certainly afford them, but considering that Wifi is plentiful where I live, it's not worth it.
Even when the local network is fast, buying a SIM card may not be an option if your phone is locked and under contract, which is very common for US users.
- People without unlimited data plans who would prefer to preserve data on their mobile plan
- People travelling abroad and want to avoid roaming fees (although I'm partial to a local sim also, for many this is quite technical)
- People who want to find a nice cafe to use their laptop
- Faster internet (Much of the world can't rely on fast LTE networks for example)
- Connectivity in places where there's no mobile signal (e.g. underground restaurants, bars etc).