First of all, I would like to state that I am against the Sangh and BJP because I consider their ideology against my view of India in which the people must remain emotionally integrated and one. But the fact remains that a party founded in 1951 is in power not only at the centre but in most of the states.
Any party or individual which is genuinely committed to a goal it considers 'lofty' has more energy and 'staying power' than the others and ultimately succeeds.
The Congress was genuinely committed to Independence and led the freedom movement, but after independence , it had no 'lofty goal 'and its leaders were overwhelmed by self interest leading to corruption and misrule.
The Socialist and Communist Parties were forced to open their membership to those who knew nothing about their ideologies, ideal and 'lofty goal ' and lost their character.
The Sangh remained committed to its goal of a 'Hindu Rashtra' and has continued to pursue it through its various organisations . It has all the weaknesses which the other parties have, but it has a passion, a dream which other parties dont have. It is that dream ( though dangerous in my view ), which is the cause of its success.
The dream would keep giving the Sangh incentive and energy and success. It would be defeated not by the strength of the other political parties, but its failure to satisfy the need and aspiration of the masses which its economic policy would be unable to do, but by then Indian society would be grievously hurt as the US is under Trump is experiencing.