In my opinion, most pain is self-inflicted. For example, because of my foolish tendencies, I lost my sense of smell. When I was eight years old, I maced myself on three separate occasions. I wanted to know if mace had a smell outside the horrible pain, and ironically, these acts of stupidity cost me my sense of smell. At the time, I didn't really have the common sense not to mace myself, I mean the first time can be an honest mistake, but the second and third time was just plain stupid. Now, as far as villainy is concerned, they end up causing themselves a lot of pain because they don't have the common sense to stop while they"re ahead. .
To illustrate this point, I"ll briefly examine Iago and Othello from Othello; Edmund, Goneril, Regan, and Lear from King Lear; Jachimo and Posthumus from Cymbeline; finally, poor jealous Leontes and opportunist Autolycus from The Winter's Tale. The common thread between all of these villains is common sense or really, the lack thereof. The first group I discuss, deal with the fools who deserve a little pity, for they have spun their stories by making bad decisions. The next group is devised primarily of cutthroats, (which is made up of most of the people above), who scheme and err somewhere along the way.
In their own ways, Lear, Othello, and Posthumus have caused their downfalls and pay dearly for them (except for Posthumus that dog!). Lear started his trouble, when he came in like a big jackass and made everyone declare their love for him. .
"Which of you shall we say doth love us most, that we our largest bounty may extend where nature doth with merit challenge" (I.1 51-53).
Now I don't know much about royalty and how they treat their family, but I know in my family, you don't play favorites. It's understandable as to why he would want to make who gets what clear, but he started off knowing that he wanted to give Cordelia complete control.