Almost everyone who is rich enough to own a high-end MacBook also owns a fast phone with a data plan, which can be used for tethering. How many cellular radios

Almost everyone who is rich enough to own a high-end MacBook also owns a fast phone with a data plan, which can be used for tethering. How many cellular radios do I need to carry with me at once, anyway? Note that this is in contrast to the iPad, where the owner cannot be presumed to have a fast phone data plan, simply because they may be too poor to own both an iPad and a fancy iPhone.