People lacked character and were cowardly due to poor culture. Buddhism had seriously curbed militancy in education and made educated people more servile in nature. Also, British arrested those who were more radical. There have been several instances of rebellion and extremism but crushed by British who followed carrot and stick approach. Subhash Chandra Bose quit to form INA for this reason.
India are cowards by nature. dont blame it on Buddhaism or anyother Religion. Historically speaking only Small Groups of Kshatriyas(Rajputs- 3.2%), Sikhs(0.5% to 1%) and Brahmins (2.2%) have forged Empires all over southern Asia from Afghanistan(Brahman shahi) to Vietnam(Champa kshatriya), Thailad (angkorwat-brahmin kings) and Indonesia (cholan kshatriya kings). total of this grand sum is at best 8%.