If you register a name because the name has brand value (e.g. Donald Trump) you will find it extremely difficult to keep without millions or billions in legal fees and then you may still lose it. Some folks don't care... they will allow you build the domain value over months or years and when you're successful then it's worth suing. The cost & loss isn't worth the sweat equity you pour in.
It's not entirely clear. In most cases where there is a UDRP complaint filed, if the purchase was in bad faith, e.g. you bought the trump address to obviously trade off his name by selling trump items, then a suit may cause you to lose the name. Do a search at wipo.org.
If it's a person name, and this person is not celebrity, you can buy it without any problem if the name is celebrity, then don't make a website about this celebrity, don't make site and wait the celebrity buy back, or make a site about a non-exist person just same name and push this celebrity to buy back.