You have given a one off example.
There are only two facts that I know of about Bangalore. Bangalore roads suck, traffic sucks. Volvo is a boon, not that I travel a lot by bus. It was expensive but convenient and hence was lapped up by the general populace even though it costs twice as much. It also depends on bus routes, but people do not think twice about paying that little extra.
Getting to the airport in Bangalore from the city center is 2 hours on a good day. Getting to cities like Mysore is 1.5-2 hours by road and Chennai is 4 hours by road. By air it is 1.5 - 2 hours to Chennai, but 2 hours just to get to the airport. So, it is equal to road travel. If HSR halves the road trip duration to Mysore and Chennai, then every Tom, Dick and Harry is going to use it like a local train. That's why the HSR is good news for Bangalore. If the HSR is extended to North Karnataka and to other cities in TN, then it will be very successful. People are there to pay for it.
Small towns won't see HSR so quickly, of course. So, no point using HSR if travel time exceeds regular services. Well, you just use common sense here, unless you don't get any tickets directly to your hometown on bad days. In 20-30 years, we may see HSR everywhere, like regular rail. It will end up becoming an inconvenience if your town is not connected by HSR. Well, your PoV may change depending on your lifespan of course. You may not want to wait 30 years to see the HSR, but who cares, the country is expected to survive longer after all. These are all plans for the long run. We may not see a HSR for another 10 years from today.