It has nothing to do with the Patriots becoming a "Monopoly" it has to do with how the team signs and develops their own players
Peyton Manning, Marvin Harrison, Dallas Clark, Joseph Addai, Dwight Freeney, Bob Sanders, Antoine Bethea (Pro Bowl last year), Kelvin Hayden, Marlin Jackson, all drafted and have only played for the colts during their careers. 20 of 22 starters for the colts SB team only played for the Colts during their careers (Booger and Adam V exceptions)
The colts develop their own homegrown talent and don't usually go out and sign "Big name" Free agents or names. Obviously Adam V was one of the few exceptions (he has one more SB the Pats do since then so I guess he had made the right decision up to now) Booger McFarland another that worked out.
Your boy Dan Klecko left for Naptown (we let him go this year but not after he did his damage especially against the pats) Deon Branch booked, Asante Samuel went bye bye, and its not like a sizeable number of players are going to turning down boatloads of money to go to Foxbourough over places on the coast and glam cities such as NY, Miami, San Diego, any time son