As you , yourself pointed out that he focused on Marketing, the answer lies there itself. Marketing without substance doesn't last long.
Let's take a look at his propaganda strategies first -
Ever since the BJP came into power in 2014 with 282 Lok Sabha seats and an absolute majority, people have been wanting to understand the phenomenon that is often called the ‘Modi wave’. With the party ruling 21 states in the country out of 29, it is no surprise that Narendra Modi, the top-gun or CEO (in a way) of the organization is a propaganda genius.
Be it the Union Government spending over 3700 crores in advertising and PR from its inception in 2014 to October 2017, the Prime Minister is leaving no stone unturned to make sure he remains the silverback of the country. If one were to dig a little deeper in the wake of the Karnataka elections (which can be considered a PR success disguised as an embarrassment), then even in terms of the party funds, BJP does not have shortage of the moolah!
How much is it making?
Quite a lot actually! The saffron party collected around 532 crores in funds during the year 2016-2017 from donations and contributions that were above Rs. 20,000. No wonder the Prime Minister would much rather demonetize to stop black money (we all know what an abject failure that was in its original objective) rather than help introduce RTI on party funds (since the BJP is clearly not one of the good guys when it comes to black money).And while the nation and its farmers await the Rs. 15 lakh that were supposed to come to all the bank accounts, and watches its PM use up his frequent flier miles abroad, there is no question to his commitment of propaganda.
Despite all this, BJP is failing!
The reasons are simple.
Only focusing on chemistry doesn't work, Maths can't be ignored.