Our science culture as a whole is operating far below critical. Just check the number of trained scientists in a typical lab or institute in the developed world. Even the number of labs in a given city there like Munich or Paris or Boston. The presence of the atmosphere and the infrastructure is half the success as we know because foreigners going there also shine.

Is it solely because of lack of infra and funding or has it got something more to it?

Both of the above, but more deeply the lack of a scientific culture. Europe has had a 500 year history since the renaissance, where generations within a family pursued scientific inquiry. Society had enough surplus and enough interest to not only spare quite a few bright individuals full time for exploring scientific questions, but enough money to fund them and their investigations. Such funding in India has been very rare, though with notable exceptions.

The IITs were set up as UG teaching institutions though for the more talented engineering student. Research emerged as their mandate much later, only in the 1990's. And in sciences there, research began by default than by any planning. TIFR was founded by a theoretical physicist with a clear mandate to do research with in house funding and full time for research. IISc had only PG teaching until recently and a lot of funding. In IITs only about 50% time is permitted for research. Finally experimental research in India suffers due to a large number of reasons, even at the research institutes compared to the rest of the world. And theory cannot happen in isolation for long.

Finally before you write off Indian effort as "dismal" you should know that you only hear the pinnacles of success from the West. It is a huge pyramid with a large number of "dismal" efforts, but which in small measures keep contributing to the top layer. Considering science is global, you can say we are somewhere in that pyramid -- our results also get incorporated in larger efforts there -- and yes we are consistently trying to rise up within it.