Those that install very wide wheels:
1) might do so because installed forced induction, for more grip. But majority twins out there most probably are and will stay NA.
2) for max grip, everything else aside, in auto-x. For hpde some reported better results with less wide wheels
3) most probable reason they add max wide they can fit, because they somewhere got this thought (maybe because many supercars have wide wheels, so due that might be some wannabe ricer thing, to fit on budget car with alike ones), that for whatever reasons it supposedly should be cool. I don't get it, as find it hard to imagine that someone actively leans/looks under parked cars to see what tire/wheel widths they have, or checks up/looks & actually cares for widths for cars driving in front of them.
In general, especially if your car will stay at NA power and if you care to not fsck up handling, don't go for max wide wheels you can fit, also don't install staggered setup (wider rear then front) which is another common mistake to do.
Or if you need more grip, then be reasonable and go upto x8 and 225 width tires. Tire compound of some grippier tire type matters more then it's width anyway.
This way you'll keep wheel & tire weights reasonable, will pay less for tires, car will be less susceptible to aquaplaning, and car will keep it's playfulness even at stock (lack of) power and at still legal speeds instead of like on rails. It may also accelerate slightly better on lighter wheels/tires then on big heavy "barrels". And by not going staggered again you won't make car understeering pig, or won't need parts to counter staggered ill-effects, be able to rotate tires for more even wear/longer mileage from set of tires, and it's easier to buy replacement for damaged wheel or punctured tire or find buyers when selling used set if it's square, instead of staggered width.
They are weird bunch of people, even buying coilovers for no other purpose but enable even wider wheel fitment then vs stock large diameter springs. But to each his own, everyone is free to pay own money to make his own car worse
.