I use wifi at home so that I can work from bed, so my wife can use her laptop from anywhere in the house, and so that my children when they come home can quickly and easily get on the internet.  All of this is done without me having to run any wires.  I use wifi at home because it is convenient.
   I also keep sensitive information on internet connected computers.
   I am not tempting fate.  I am using my brain and knowing that my sensitive information is safe behind a firewall and password protected router.  I refuse to listen to people who lie and warn of things that are not possible to happen just so they can instill worry and fear (and sell their unneeded product).

Perhaps my experience is colored by my part time job, research for corporations, sometime government agencies.  Sometimes I have sensitive information that belongs to others so I encrypt my usb drives, external hard drives, and some files on my internet connected hard drives, but keep most sensitive information off the constantly connected hard drives.

I use a pass worded router, the top software firewall according to Matousec, and I feel that my security is sufficient.  Sufficient is not perfect.  There is no need to keep credit card numbers, bank card, Soc. Sec., or any such numbers on your hard drive. So why do it?  

You can secure wifi but even the latest encryption standard has been hacked.  I just give my opinion as security researcher.

Friends say that the NSA could not hack into my networks (unless they got physical access to it, maybe.), but I don't assume that's so.

I have 4 laptops, 2 with XP Pro, but I seldom use them wireless. When I do use them wireless - both have the top firewall, each has a anti virus in top three according to AV-Comparatives- I am very careful, and use Firefox with RefControl, NoScript, and CS Lite. Run the browsers sandboxed. I have a laptop with Leopard, a Mac, and one with Ubuntu. The one with Ubuntu I use 90% of the times I use a laptop wireless. The OS aimed at by hacker is most times a Windows one.

I run all my browsers sandboxed.

None of my measures require much input once setup.

I am a cyclist, love camping, the out of doors, have a spiritual connection with all, and the holy creator of it all. So I have a bias against use of computers out of doors. When I am outside I am computer free, except for my mobile (but it's off half the time), and I use computers most time indoors.  Wireless is convenient, and probably safe with firewall, anti virus, and encryption.

I research the hacks, the corporate breaches, and the unpatched  weaknesses in software; that influences my views.  I offer my suggestions to help.

Be scared a bit, it makes you careful.