For me, the reason is financial instability.
Earning upto 2 lakhs per month feels like nothing in today's time. After taxes, education loan EMI and expenses, one is barely left with anything. On top of that, I have an added responsibility of catering to my parents and need to send the money every month. My savings are a mere 15K per month and I don't think I can get married at this stage. Further, I don't have the bandwidth to have kids.
So I have kind of accepted how my life would be. No marriage. No kids. Slog till I have to take care of my parents. The day I am free from that responsibility, quit the job and start working with an NGO with an aim to make living better in India. Would not want anyone from the future to live life like me and for that, someone needs to be there and drive that change.
My family would be that NGO and all the beneficiaries from that NGO.