Many years ago the same logic was applied to Canary Wharf, many simply couldn't understand why the developer was building a new 'city' right slap bang in the middle of a wasteland where crime was rife.
I along with a few other bought as much land adjacent to the big developers as we could get.
At various pionts we sold as the 'new' developments surrounding it spread and transformed the area, there are of course still parts that could do with being laid waste and rebuilding - and in time that will happen.
I expect that much the same transformation will happen in area around Tottenham - but the local council and the Police will have to step it up - in much the way we forced Newham to do when it was clear they were criminally inept and too used to let the area sink into a cesspit.
Spurs and others investing in the area (and there are many planning too) will have to force the issues - because a rising tide raises all ships and improves the quality of all lives; and sadly at the moment the local authorities around the new stadium are now too embedded in the past to understand how destructive their socialist dogma will affect the way the area could evolve.