Why do people use Wi-Fi when they already have data on their phone?

Deal with the troll before it's too late. Every question in th.answers.yahoo.com has tons of blank answers (using space bar); it could have been posted by someone like Shadowfire to gain points for his troll accounts. In his questions and answers he always refers to Christian Lord God as “lord” / “god”; basically, when using proper grammar throughout his hateful blasphemous speech, he deliberately writes these two words from lower case letter. Jewish user Shadowfire (who spams this link “deathmetal.org/news/christ-sodomized” and has been on Yahoo Answers since the beginning and could possibly be the infamous homosexual flying antichrist from the tribe of Dan) from Portland [or so he claims because he could’ve been born in Russia in Valday (Russian: Валда́й) to a 12th generation Jewish prostitute who pretends to be a virgin)] has many trolls accounts on Yahoo Answers. These could be his accounts: Blackthorne1979, James Blackthorne, ✟ summer of night omega crow † ⚔, Saint James Tiberius Troll, Lord Shadowfire, Carter Berg, Madam Sin Bin, Fireball, Aravah, Miguel, ThatToiletguy, Tublet Huglet, Tut Uncommon: 3peat Offender, Cult Free, Reynaldo Weeks, Juli, Petri Lindroos, Uncle Fester, Lord Ninigi, Knightwulf, Nonplussed, Nightwulf, lyconpolis (lycon = wolf), Derick Fields, Toilet John, Hitler Was Right About The Jews, Master Debator, Magistra, Desiree, D-girl, Firecock, Yahoo User, Corvus Blackthorne, Patrick McCluskey,  Lord Aizen, Torchbug, Arni, r.wolfpaw, No Bozos, Fuzzface McGee, First Dragon, L.E. Gant, Fullofpoop, Shadowfire the Sarcastic, Pope of Atheist God, Jimson C. Raskin,  

A yellow face with simple open eyes showing clenched teeth,

El Nerdo Loco, megalomaniac, Corvia Blackthorne, Shadowfire Lives, Shadowfire Lives bytches, The Chick that wears Doc Martens, Homo, Wotan 8, Wotan (who keeps posting “satanisgod.org”), Heidi Ho, Clo Bird, Angels with Silver Wings, Orange I'lluminaughty, Christian Sinner, Gandalf the black, The Lord Hummungus, Mismatched Tube Socks, Pearl, Partysnax the Dragon, etc. and any other anonymous accounts. With one his accounts Fireball, he pretends to be a Methodist old lady who posts short-hand slang TIRH (this is religion here). He reports all answers and questions that he doesn't like just so that his questions stay on top in the Religion and Spirituality section. He trolls in other categories too. It gives Christians a bad name (just because of this troll's sock puppet account). His Toilet John account keeps posting questions where Jesus was sodomized by Roman soldiers. Remember the prophecy where it says that the antichrist will have personal hatred towards the real Jesus Christ. That’s why Shadowfire keeps posting thousands of similar questions along the line: “Did Romans sodomize Jesus?” or “Was Jesus anally violated during the crucifixion?” or "How many liters of cûm did Jesus swallow before being hanged on the cross to die?" or "Did Jesus take a big dick up the butt beforr dying?" or "Did Roman buttfck Jesus before crucifying him?" or “Did Romans buttrape Jesus?” or “Did Jesus spend his final hours feasting on Roman feces, sucking Roman cocks, and juggling one erect dick after another up his butt?

“ or “Is it true the Romans relentlessly sodomized Jesus, came all over his face, shat in his throat, pissed in his anus, & left him dripping wet?

“. He asks multiple idiotic mundane questions like “Is Hinduism true?”, “What makes a girl harden?” [like he enjoyed killing little girls], etc. and answers them with his sock puppet accounts just to gain points. Some questions you can see that he answered with like five or seven accounts (especially the ones about himself that he reports right away). With his Reynaldo Weeks account he boasts that he was the reason why their accounts were suspended. With his Magistra account he threatens people with clowns and CIA assassins. Shadowfire mocks Christians with his sock puppet account Fireball in the Religion and Spirituality section by answering very destructively and adding "TIRH here" or reported (anonymously) or “fck you nigers”. He gives Christians a bad name because he promotes sins like sodomy, fornication, ecumenism, astrology (horoscopes), etc. He should be executed and burned at the stake for blasphemy. He spreads rapture heresy, reincarnation heresy, ecumenism heresy, etc. and many more subtle heresies. Antichrist will ride on a donkey into the 3rd Temple. Stop him before it’s too late. Antichrist is gay flying wizard who was born from a prostitute and who will ride on a donkey into the 3rd Temple. Antichrist's mother is a 12th generation prostitute (according to saint Lavrentiy of Chernigov). According to researcher Grigoriy Klimov, prostitutes = lesbians = witches; so, antichrist's mother is a witch, a lesbian, and a prostitute. Hide your kids, hide your wife ‘cuz de evil antichrist is flying thru town; take your glocks out and shoot dat son of a bytch down! Again, he’s an s-o-b ‘cuz his mother is a prostitute to Jews and Hindus. Funny thing is that she pretends to be a virgin. Don’t be deceived by this skumbag and his fake miracles trying to emulate Christ’s miracles! If wrongfully accused, forgive me; state under your account that you are not Corvus Blackthorne then. Shadowfire claims to be extraterrestrial raven when demons pretend to be extraterrestrials. I’m paranoid and think that all Yahoo accounts that talk about ravens are about him. Please, help me; I beg you. Using user Miguel, he’s teaching people how to summon demons. Dirty, very dirty! Shadowfire is a true dirtbag; do something to stop him now; he’s only one user and he’s doing the harm like it’s hundreds of users.

Not everyone has a Mobile phone or a Laptop or a Tablet and io only use wi-fi when my Internet goes down

They want to save on data costs by doing it. Simple as that. 

For security reasons. If you don't know that, don't use a smartphone that's smarter than you.

WiFi has more broadband, which means you can do more stuff on it without the speed slowing down, data's connection usually slower and weak, with less broadband, which means it can't take as much stress. So even if you have unlimited of both, WiFi is usually the better option if you have a strong connection. Hope this helps.

Unlimited data and more bandwidth for working at home, streaming movies, connecting all my smart devices and the list goes on and on.........

Because I pay for my WiFi, and it's easier than using my data which I might need if I'm out and about. 

Wifi is generally free (due to probably already having internet for other reasons), and it lets people save data usage for emergencies or what not

When your at home, you should use your wi-fi because it saves data on your phone.

Wifi is faster for some things. Plus my data slows after x usage.