Access to better schools is a factor in selecting a locality within the city but I don't think it has been a deciding factor in deciding the city itself.

Many cities including tier-2 cities have a variation of one of those "international" schools that parents seek and there's no significant difference in the quality of education between them.

Apart from the usual cycle of available talent + job opportunities, Bangalore has better weather and location wise it can attract talent from 4 states(these 4 states are major contributors to IT workforce compared to other states) while not being too far from place of origin.