Is there really parity in the NFL?

I was pondering the question about parity in the NFL.  Since I really started following pro football, i have not seen nearly as much parity as one would think.  The salary cap is set up so that no team can dominate.  It rewards bad teams with high draft picks and an easier schedule.

But think about this: rich owners (and they are all rich) can no longer get fed up with losing and purchase a bunch of good players.  They are a group of multi-millionaires and billionaires who are used to buying and demanding their own way.  

And while they have strong buisness acumen, they rarely have the combination of skills that makes a succesfull general manger.  

Unfortunately, since they are making the payments, and are used to calling the shots, they usually do more harm than good.

So since the salary cap prevents quick fixes and prevents angry owners from addressing needs quickly and making up for years of bad mistakes, the NFL is becoming less even.  Consider that the Patriots, Steelers, and Colts have dominated the AFC for the last decade.  

Consider that ownership can sometimes be such a handicap that they are unable to win.  Some owners inherited the team or inherited the money to buy the team; they have to go up those few organizations that have been investing and focusing on improving their teams for years and year.

I think that is too much of a handicap for some owners to overcome and therefore, some entire franchises.