Over-estimating is one thing, but we should understand their mindset because that is critical to predicting their moves. The revocation of article 370 was a direct result of this fantasizing. Remember that both the Chinese and Pakistani leadership was surprised by this move. When you're surprised by a move your opponent makes, that means you failed to understand your opponent.
The cause of this failure was a lack of understanding in how deeply rooted the BJP is in the RSS's ideology. All this fantasizing comes from the RSS, which is the support base of the BJP, which has filled India's military, bureaucracy and media with sycophants. I earlier listed the political reasons for India joining the US-led Quad. But as I mentioned, there are complex historical reasons for this Quad alignment as well. Well, here's a quick summary of this very convoluted dimension:
The RSS/BJP believes that in order to secure its Greater India/'Akhand Bharat' fantasy, it will need the US on its side. This isn't just because the US is an opponent of China, but because in the RSS's ideology, the United States is a fellow 'aryan' nation. Yes, this is the same 'aryan race' idea which Hitler used. This 'aryan' concept probably originated in Europe with the British, who literally invented modern racism and then spread it all over the world via their global empire. The RSS later adopted this racist ideology as an insecure response to India's historical domination by the Muslims, allying with the Islamic Civ's nemesis, the West, which itself invented the 'indo-aryan' concept to justify its own 'Caucasian' superiority...
You can see how crazy this all gets and right quick. But there are multiple leaders in the US/EU/India whose support base (not all, but a significant chunk) believes in these ideas. Here's one source, but you can find many others:
p.s. The RSS's fantasy maps can range from this:
To this:
To sometimes this (lolz):
Quick question, what is RSS?