Well he hasn't exactly kicked on or developed into much more than an also-ran midfielder who is there mostly to take up home-grown space and act as injury cover.Transfers also take more than 1 party. Spurs is Winks' club since he was a 6 year old kid, its clearly his dream job and no doubt he knows once he's left the chances of him coming back are pretty low. He's not a football vagabond, its completely possible Winks views being a bit part squad player for Spurs more desirable than a bigger role at Watford or Burnley.
Winks has been at Spurs for 19 years. Pretty sad how some of the "fans" treat him.