There's no support for athletes there, poor infrastructure, and unheard of levels of corruption.
Cultural differences; indian parents don't value sports as a career, they'd rather their kids study. Plus, they only want to play cricket.
Class/caste systems; the majority of poor, talented athletes will probably never be noticed, and the rich ones are mostly lazy or egotistic. When I say lazy or egotistic I mean they've grown up with servants around the house, can you imagine them being trained by someone lesser than them

. Sadly these are the only ones that can afford professional development and bribes.
The poor probably can't afford the bribes to get in. If they do well at the olympics they'll be treated great, but if not you might find them begging on the streets a few years later. If you get injured, then what?
The money the government would spend to develop coaching and facilities for olympic sports is eaten at every level and there ends up being crumbs to actually train athletes.
I've never lived in India but I've been there several times and I'm telling you brehs, the corruption is endless