the trend of other major armies.

2 major reasons I guest:

1)Hindu unemployment is the most serious national issue there and they must recreate more jobs

2)It helps the promotion prospect of junior to middle ranking officers

The hindus spend something like 2.6% of the GDP on their military(as against china's 1.9-2.0%). And 62% of their army budget was spent on salary alone(see the table below.Yes salary alone.Housing, fringe benefits like medic care for dependents are outside that 62%). The main sacrifice is ammos stockpile, training and readiness,not to mention state of equipment. Their budget for an army of over 1 million(not counting 'paramilitary') is simply insufficient.
There's no such thing as PPPee military budget(IMO.that PPP GDP is voodoonomics). Even the food consumed by soldiers have internationally reference prices and developed countries usually can produced bulk food cheaper.https://2.bp.blogspot.com/-NfvCsem1IAE/VtxKOpb7F_I/AAAAAAAAGdo/9r7j9wBGVnU/s1600/1457202266-2941.jpg  (Mao clone's note of caution: the following figures,well known to those who have done some search, do not include pensions,which is substantial given the size,nuke/ballistic weapons, paramilitary  and other items better hidden)