The story starts way back. In general the schooling syllabus in India is very broad and deep (I can say this now since I live outside India). Then due to the large population - around 30 million students complete school every year. After that there are not many good universities (you may have heard of IITs or NITs), only around 100-200K get into good unis. The competetion to get in is therefore intense. Preparation for these "entrance exams" can start at age 15 (or even earlier).
If someone makes it somehow, graduation, postgrad and MBA is another similar struggle. Now you think you surely made it. The last 7-8 years of intense work and hardship are over, this is doubly true if the person is not from a well off family in India (which is very common). Preparation schools, hostels, being away from family etc. has its mental costs.
Then you land a job and it hits you, as a new joiner in the hugely competitive Indian job market you are treated like sh* and all this while you thought "you made it" but the real struggle has just started. Long working hours, immense pressure and then the thought that all the hardwork you did in the past can come crashing down with one bad review. Combine that with the real stuggles of life as you move to a new city, manage finances, support family back home etc. it creates a huge amount of pressure. Some unfortunately are not able to handle it, they are in a position they feel that all was futile and no one can understand their situation.